Photo by Rantje Allen
Photo by William Tan
Photo by Rantje Allen
Photo by William Tan
Photo by Rantje Allen

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Tag Archives: Diving Gorontalo

Bigfin reef squid mating dance

Posted on March 15, 2026 by Miguel's Diving • 0 Comments

Bigfin Reef Squid are a fascinating sight for divers in Gorontalo. Often, small groups of these squid hover in open water above the reef slope.

Mating Dance Captured on Video

During courtship, their bodies shimmer with changing colors and patterns. Only the luckiest of divers witness this remarkable mating dance of flashing colors and synchronized movement. Ted Foon, one of our guests, captured several minutes of this rarely witnessed behavior. We share highlights in our YouTube video.

Identifying Bigfin Reef Squid

The squid in this video is the Bigfin Reef Squid. Its scientific name is Sepioteuthis lessoniana. Its large oval fins make it easy to recognize. They run almost the entire length of the mantle. These fins give the squid a shape that resembles a cuttlefish. The body is semi-transparent. But it can flash brilliant stripes or waves of color. Scientists believe that these color changes help squid communicate during courtship and competition.

Bigfin Reef Squid typically grow to about 30 centimeters in length. They are common throughout the Indo-Pacific. Often in small groups, these squid gather in shallow water near coral reefs, seagrass beds, or mooring lines. During mating displays, males may guard a female while rival males attempt to approach. The rapid changes of color and pattern are part of this visual communication. However, in our video, no other males were present.

Conservation & Natural Observation

Reef squid are important predators in coral reef ecosystems. They feed on small fish, shrimp, and other crustaceans. In turn, they are prey for larger fish, dolphins, and other marine animals.

Encounters with Bigfin Reef Squid are most memorable when divers remain patient and respectful. When divers maintain a distance and move calmly, the squid can continue their graceful courtship displays. These moments reveal the remarkable intelligence and beauty of reef cephalopods in their natural environment.

Squid are highly intelligent and show awareness of divers. If a diver spots a group of them, the squid will retreat by swimming backwards until they disappear from sight.

For your chance to see squid hovering over Gorontalo reefs, make your dive booking directly with us.

Grand Side-Gilled Slug Takes a Day Trip

Posted on January 5, 2026 by Miguel's Diving • 0 Comments

As large as a dinner plate, the Grand side-gilled slug delights divers during night dives. But during the last day of 2025, one crawled across the bottom in daylight.

A Nocturnal, Giant Sea Slug

Most divers are familiar with nudibranchs. They have feathery gills exposed on the top of their bodies. Side-gilled sea slugs are different. Their large, plume-like gills hide between the mantle and the foot. They are usually tucked along the right side of the body. This unique arrangement gives the group its common name.

Grand side-gilled sea slugs live primarily on shallow sand and rubble bottoms. They are almost exclusively nocturnal. This behavior makes them ideal targets for sightings during night dives. After dark, they crawl across the sea floor, actively hunting tunicates, anemones, and other invertebrates. With strong jaws and a wide mouth, this species can even consume sleeping fish.

Like other members of this group, the Grand side-gilled slug has a pair of rolled rhinophores. These detect chemical cues and water movement, helping to locate prey in the absence of light. When threatened, it can secrete sulfuric acid as a chemical defense. As a result, most predators avoid this giant slug.

The Grand Side-Gilled Slug

The Grand side-gilled slug is the most commonly seen species of its kind in Gorontalo. It can grow to an astonishing 21 centimeters. It may be the largest sea slug divers are likely to encounter. Its scientific name is Pleurobranchus grandis.

Its coloration varies widely. However, the species usually displays three dark bands that contrast sharply with the rest of its body. When moving, the slug can arch its mantle, forming a raised spout toward the rear. This structure helps channel water and waste away from the body as it travels across the seabed.

Despite its size, P. grandis moves deliberately and calmly. Notice its subtle movements in our video.

Surprising Sighting in Gorontalo

Imagine our surprise and delight at finding a Grand side-gilled slug crawling in broad daylight. Fortunately, one of our dive masters had an underwater camera ready to capture this moment. Given that the date was December 31^st, we speculated that it was on its way to a New Year’s Eve party.

For your chance to make an unexpected encounter in Gorontalo, make a booking with us.

Pinktail Triggerfish & its Coral Hideout

Posted on September 8, 2025 by Miguel's Diving • 0 Comments

Pinktail Triggerfish, stylish and sleek, delight divers lucky enough to see even one, especially fans of pink. Although only occasionally found in Gorontalo, its coloration is bright and distinctive.

In the Pink

This fish’s body color is dark, from olive-brown to almost black. This helps the fish blend into the shadows of the coral reef. However, its active tail is magenta/pink with a distinct white base where the tail joins the dark body. Its elegantly paired dorsal and anal fins are ghostly white and edged in black. Yellowish are its pectoral fins and snout.

Many fish species can lighten and darken their body colors. If a Pinktail Triggerfish is in lighter mode, a crosshatch pattern appears on its body.

Its official name is Melichthys vidua. The genus name means “black fish” in Greek.

Active & Shy

Divers will find this fish both active and shy. Only when a Pinktail Triggerfish is hunting for food will it allow a closer approach. This fish eats mainly algae and detritus. However, using its dental plates, it can also eat crustaceans, octopuses, sponges, and even small fishes.

Locking a Trigger

The Pinktail Triggerfish has a locking mechanism in its dorsal fin spines. This body feature is unique to all triggerfish species. The fish can erect its first dorsal spine and lock it upright using its second spine. In order to unlock its trigger, the fish must first depress the second spine, allowing the first one to relax.

Triggerfish that feel threatened quickly jump into a hole or crevasse in the reef. By locking the trigger, it is wedged in and cannot be pulled out. The predator can only nip the edges of its unprotected tail while the fish hides.

Where to Find Pinktail Triggerfish

This delightful fish lives through Indo-Pacific region, including Tomini Bay where Miguel’s Diving offers scuba diving. Although this fish can gather in schools in other ocean locations, we only see it singly in Gorontalo.

Divers here will most likely see it in very shallow waters on coral rich dive sites where ocean currents sweep by. In other places, scientists have found it below fifty meters.

Since divers are unlikely to spot a Pinktail Triggerfish unaided, ask one of our dive masters to point one out during your diving day.

For your chance to make memories in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

The Black-Blotched Porcupinefish: Spiny, Shy & Striking

Posted on July 26, 2025 by Miguel's Diving • 0 Comments

A most unusual fish divers see while diving in Gorontalo is the Black-Blotched Porcupinefish. Most noticeable are its large head and big eyes. Short, strong spines stick out from the back half of its body.

Striking patterns of the Black-Blotched Porcupinefish

Divers can easily recognize a Black-Blotched Porcupinefish. In the video shot while diving Gorontalo, notice its large size. Also striking are the broken dark bars on its face and head. Note the big black blotches on its back and sides. Its fins are yellow. Standing out against its grayish brown body are its white spines.

The scientific name for this fish is Diodon liturosus.

Fish Habits

This fish often hides under rocks or swims slowly along coral reefs. Its large eyes help it while hunting at night. Crustaceans and mollusks compose its main meal. The fish’s beak-like teeth crush the hard shells of these invertebrates. Notice in our video that the fish searches the sandy bottom for something to eat.

A Ball of Spines

When a Black-Blotched Porcupinefish feels in danger, it has a special way to protect itself. It quickly gulps water and swells. This makes its spines stick out. The fish becomes a ball with sharp spines. As a result, predators do not want to eat a fish like that. This defense is common in porcupinefish species.

Divers might see two other porcupinefish species. One is the Spot-Fin Porcupinefish (Diodon hystrix). It has many small black spots all over its body and fins. However, it lacks dark blotches or bars on the face. The second is the Long-Spine Porcupinefish (Diodon holocanthus). A net-like pattern covers its body. Although it has big eyes, it lacks the large blotches of the Black-Blotched Porcupinefish. Also, the spines are longer and thinner.

Good Behavior for Divers

Even though porcupinefish look friendly, divers should approach with caution. Do not chase or touch them. Never try to make one inflate. This stresses the fish since it thinks you want to eat it. At Miguel’s Diving, we believe in safe and respectful diving.

Porcupinefish also contain tetrodotoxin. This is a potent neurotoxin that makes them unpalatable or deadly to most predators and humans.

Since this fish is rarely encountered, seeing a Black-Blotched Porcupinefish during your dive will make a special memory.

For your chance to make memories in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Location of Miguel’s Diving Gorontalo

Posted on June 20, 2025 by Miguel's Diving • 0 Comments

Location is key for any business, including Miguel’s Diving. Less than an hour from Gorontalo’s airport, our dive center rests in a safe location inside the Bone River. This provides direct access to the vast Tomini Bay.

Our Airport Code: GTO

Daily, direct flights from Jakarta land at Gorontalo’s Jalaluddin Airport. It is modern and spacious. Our package options include airport transfers. Upon exiting baggage claim, divers simply look for a driver holding a paper with their names on it. The ride into town is less than an hour.

location of Miguel's Diving — Our Google Earth location

One option we offer is diving upon arrival. This is possible for passengers of Batik Air whose flight arrives here at about 8 a.m. Prior arrangement is required.

Google Map Location

Finding us on Google Maps is easy. Just type in Miguel’s Diving Gorontalo in the search bar. This is our location link.

However, this location is about five meters off, which is within the error margin for Google Maps. Travelers can be confused when they arrive at a block ice factory used by fishermen! Google still has a picture of this blue factory for its street photo of Miguel’s Diving. Actually, we are the two-story yellow building next door. A huge dive flag is painted on the street-facing side of our dive center. Slide the gate open and enter.

To help travelers visualize our location, we have created a short video that starts in space and zooms all the way into our dive center in Gorontalo. It includes satellite animation using Google Earth, plus drone footage of our dock, dive boats, and the expansive blue waters we explore daily during dive season.

Strategic Dock Location

Our dive center and dock are located just inside the estuary of Bone River. The name is pronounced boh-nay. This gives our divers a clean, secure area to organize gear prior to diving. They can also relax there after the dive day.

Travelers may question why we do not anchor our boats along the ocean. Because of Gorontalo’s unique geography and rapidly changing weather, that option is not wise.

Also, we guard our speed boats round-the-clock against sudden storms and waves. Over our two decades of operation, our strategic location and dedicated staff have prevented our boats from damage or sinking.

Miguel’s Diving is located along the northern coast of Tomini Bay in Sulawesi, Indonesia. This bay is one of the deepest in the world and offers pristine diving conditions and rare marine life—like our iconic Salvador Dali sponges.

To assist in your dive trip planning, please make your dive reservations directly with Miguel’s Diving.

Thysanozoon nigropapillosum Swims & Dazzles

Posted on April 10, 2025 by Miguel's Diving • 0 Comments

Thysanozoon nigropapillosum is a dazzling flatworm. Yellow- or gold-tipped papillae cover its black body. Its body margin has bold white edges.

Many Confusing Names

Thysanozoon nigropapillosum lacks a standard English name. Some call it the Yellowspotted, Yellow-spotted, Yellow Spot, or Yellow-speckled Flatworm. Others refer to the spots as gold. Some online sources call it the Galaxy Flatworm since its body looks like a maze of stars.

Appearances of Thysanozoon nigropapillosum in Gorontalo

Before opening diving in Gorontalo, Miguel’s Diving surveyed potential dive spots. In May 2000, we recorded our first sighting of Thysanozoon nigropapillosum off the coast of Bone Pantai Regency. Since then, we have rarely encountered this beautiful flatworm—perhaps only once every five years!

In 2025, one of our guests captured Thysanozoon nigropapillosum on video, creating an intriguing clip. Flatworms can swim short distances by waving their flat bodies. The video shot by Rainer de Reuter captures this undulating motion perfectly!

Notice the two white-tipped protrusions at the front of the flatworm. These are pseudotentacles. They sense light and motion, helping the flatworm navigate.

Favorite Food

Thysanozoon nigropapillosum feeds on certain species of tunicates. One of its favorites is Didemnum molle, which is very common in Gorontalo. The flatworm engulfs the tunicate’s thin body with its mouth. However, it does not digest the hard calcium spicules that give the tunicate structure. Instead, these are expelled as pellets.

Savage Mating

All flatworms are hermaphrodites, meaning they have both male and female reproductive organs. Thysanozoon nigropapillosum also has two penises. During mating, each flatworm attempts to inseminate the other. First, special structures called rhabdites grip the partner’s edge, providing a strong hold even while swimming. Then, the two try to stab each other with a penis—or both! The maze of yellow papillae makes aiming difficult, and missed attempts often result in dermal impregnation.

Where to Find this Dazzling Flatworm

Found throughout Indo-Pacific waters, this dazzling flatworm can grow up to 8 centimeters long. Divers can spot it at depths ranging from one to twenty meters.

For your chance to see unusual marine life in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Striped Barracuda Warily Eye Divers

Posted on December 5, 2024 by Miguel's Diving • 0 Comments

Striped Barracuda schools on Gorontalo’s shallow reef flats. Smaller and more cautious than its larger relatives, this species dazzles with its streamlined body.

How to Identify Striped Barracuda

In contrast to other barracuda species, the Striped Barracuda is smaller, reaching about 55 cm in length. Also, its body features two thin, dark horizontal stripes running along its silvery body. These stripes are its defining feature and help divers distinguish it from barracudas that look similar.

Sometimes, it is called the Obtuse Barracuda, which translates its Latin name of Sphyraena obtusata.

Other Barracudas found in Gorontalo

Occasionally, divers in Gorontalo will see a Great Barracuda (Sphyraena barracuda). As the largest barracuda species, it can grow over a meter in length. Often, it swims alone. Its imposing size and solitary nature make it easy to differentiate from the smaller, schooling Striped Barracuda.

Also found in Gorontalo is the Yellowtail Barracuda (Sphyraena flavicauda). As its name suggests, its yellowish tail is the most prominent feature. Its body has faint spots instead of the distinct stripes seen on the Striped Barracuda.

The Black Barracuda (Sphyraena qenie) is slightly larger than the Striped Barracuda and is known for its dark fins and body markings. While the Striped Barracuda has clean, horizontal stripes, the Black Barracuda’s markings can appear as a combination of dark smudges and irregular lines, giving it a more shadowy appearance. These features, along with its tendency to inhabit deeper waters, help divers tell the two species apart.

Habitat and Behavior

striped barracuda school — *Sphyraena obtusata* school in Gorontalo

This barracuda species is found in warm, shallow waters throughout the Indo-Pacific region. They prefer areas with coral reefs, mangroves, and seagrass beds, where food is abundant.

During the day, they form schools for protection, creating a shimmering spectacle as light reflects off their bodies. At night, they disperse to hunt small prey like fish and crustaceans.

Tips for your Encounter with Barracuda

The schooling behavior of the Striped Barracuda is a visual treat for divers. Seeing these sleek fish glide in unison over Gorontalo’s colorful reefs is unforgettable.

barracuda wary of divers — Barracudas are wary of divers

However, their cautious nature makes observing them tricky. We suggest divers move slowly, so as not to startle them. Also, try to approach from different angles. The barracuda school will maintain distance from divers if it feels threatened.

An encounter with a school of Striped Barracuda offers divers an opportunity to appreciate the beauty and diversity of the underwater world. So, plan your dive with Miguel’s Diving to explore Gorontalo’s vibrant marine life up close.

Schooling bannerfish found near pinnacles

Posted on August 30, 2024 by Miguel's Diving • 0 Comments

Schooling bannerfish are a rare sight in Gorontalo. Divers can see these beautiful fish at only two less-dived sites.

Trailing white ribbons

Like graceful dancers pulling long, white ribbons behind them, Schooling bannerfish are a distinctive addition to any dive site. The adult fish’s white dorsal fin extends past its tail. This looks like a long banner trailing behind the fish as it swims. Actually, this banner is only the first rays of its dorsal fin. The remaining dorsal fin is thick, deep yellow, and hugs close to the body.

Overall, the fish’s body is white, tall, and flat. It sports two large black bands. These bans cross the body diagonally. Also, the tail and pectoral fins are yellow. The fish’s snout contains a few dark spots.

Schooling bannerfish in Gorontalo

Although this fish lives through Indo-Pacific waters, divers in Gorontalo are not likely to see it. Schooling bannerfish only live in two dive sites here. These sites are rarely visited, and only Miguel’s Diving staff know where to find them. The rarity of this beautiful fish is one of the marine mysteries of the area.

In Gorontalo, this fish stays close to certain coral pinnacles. As ocean currents flow past the pinnacles, these bannerfish feed on passing plankton. As the common name suggests, Schooling bannerfish swim in schools.

Confusing, similar species

Although Schooling bannerfish have unmistakable features, determining the exact species is difficult. Moorish idols also have trailing white dorsal rays. However, they stay in pairs and close to coral rich reefs where they feed on coral polyps. They also have an unmistakable, bright orange patch on their snouts.

Bannerfish with long dorsal fins come in two seemingly identical species. They are Heniochus acuminatus and Heniochus diphreutes. In H. acuminatus, the rear edge of its anal fish is more rounded. In H. diphreutes, the rear edge of the anal fin aims almost straight down, coming to a sharp point. That sharp point is basically half white and half black. Moreover, H. diphreutes has a rounder face and generally feeds on plankton in the water column. H. acuminatus tends to feed nearer the substrate, have a longer snout, and can travel in pairs or even alone.

Both species have numerous common names. One common name for H. acuminatus is the Longfin bannerfish. Its other names are Pennant coral and Reef coachman. H. diphreutes is usually called Schooling bannerfish.

For your chance to search for this beautiful fish in Gorontalo, make your dive reservations directly with Miguel’s Diving.

Black Velutin Snail makes rare appearance

Posted on July 8, 2024 by Miguel's Diving • 0 Comments

Coriocella nigra, or the Black Velutin Snail, so easily hides that divers rarely see it. However, one day this dive season, staff found one during the safety stop. This one was only the second snail we have seen in over twenty years of diving here.

Coriocella nigra, a rarely seen snail

The Black Velutin Snail is so unusual that it gained its own genus. In 1824, Henri Marie Ducrotay de Blainville created a new genus and species for this snail. He named it Coriocella nigra. This name is still valid today. At the time, there was only this one species in the genus Coriocella. Currently, there are several more, based on more recent scientific studies.

It lives in rocky environments from very shallow depths down to about fifteen meters. The one in our photo measured about 8 centimeters long. This snail can grow a bit longer. Although found throughout the Indo-Pacific region, divers rarely seen it, despite its size. Natural camouflage disguises it.

Researchers speculate that this sail eats tunicates. Traces of octocoral have been detected in its intestines.

Varying Descriptions of the Black Velutin Snail

The color of the snail’s body is usually black or brown with shaded highlights in different colors. The Coriocella nigra that we found here in Gorontalo was unusually yellowish.

Most distinctive are the many smooth lobes that project from the main body. A closer look will reveal a longer projection at one end of the Black Velutin Snail. In our photo, it appears on the lower left. This is the snail’s inhalant siphon. Underneath the siphon will appear tenacles. On the tenacles are the snail’s eyes. Our snail was at rest, so its eyes were tucked inside.

Shell in a Snail

Unlike most types of snails, the Black Velutin Snail lives outside of its shell. Its shell is entirely inside! The shell of Coriocella nigra is translucent white. It usually contains two and a half whorls. However, the largest snails will have grown three whorls. It is thin and delicate. The length of this internal shell will be about a quarter of the length of the snail.

Although divers are unlikely to see a Black Velunid Snail anywhere in the world, they can see many other delightful creatures in Gorontalo. To do so, please make your dive reservations directly with Miguel’s Diving.

Sargassum frogfish delights divers

Posted on November 23, 2023 by Miguel's Diving • 0 Comments

Sargassum frogfish float on surface currents to dive sites in Gorontalo. Our diligent diver masters know how to find them, to the delight of guests.

Floating Refuge

As their common name implies, Sargassum frogfish hide among sargassum weeds. Although these weeds initially grow along shallow ocean bottoms, storms will rip them up. Then, these weeds will float on the surface. They have air-filled bladders that look like berries, which helps the weeds float.

Over eighty species of fish use floating mats of Sargassum weed for part of their life cycle. Juvenile fish can hide there from predators. But predators also lurk unseen among the weeds.

Camouflaged Predator

One such predator is the Sargassum frogfish. Like other frogfish

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, this one has a small lure between its eyes and mouth. When the fish is hungry, it will wiggle its lure to tempt prey to approach too closely. With a sudden, giant gulp, the frogfish will ingest the small fish, crab or shrimp. Unhappily, baby frogfish may also be devoured.

This frogfish’s scientific name is Histrio histrio. It is the only species of this genus and no other fish looks quite like it. Its appearance is unmistakable, although finding it is difficult. Its coloration mimics that of Sargassum weed. Also, it has fleshy appendages that look like its weedy host. Although it can swim, this frogfish usually remains motionless. Instead, it grabs onto weeds with its pectoral fins and tail. When necessary, it can alter its color from lighter to darker, or vice versa.

Techniques for Finding Sargassum frogfish

Our dive masters are skilled in finding these shy and delightful critters. During surface intervals between dives, they will search floating weeds near the dive boat. If they find one, they will scoop it into a small bucket along with the weed on which the frogfish clings. That way guests on the dive boat can see it up close. Although this frogfish can survive quite a while above water, we always return it safely to the ocean.

For your chance to see a Sargassum frogfish Gorontalo, please make your dive reservations directly with Miguel’s Diving.