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

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Category Archives: Marine Life

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.

Hawksbill sea turtle observed naturally

Posted on February 27, 2026 by Miguel's Diving • 0 Comments

Hawksbill sea turtles are a common sight for divers in Gorontalo. In our video, one sea turtle feeds under coral, scratches beneath its flipper, and swims to the surface to breathe. Because the divers stayed calm and kept their distance, the turtle acted naturally. It did not flee or show stress. Respectful diving allows turtles to behave as they would without humans nearby.

Responsible Diver Behavior

Good diver etiquette is key. Divers must maintain good buoyancy, avoid sudden movements, and never block a turtle’s path to the surface. Also, divers must never surround a turtle, lest it fear being attached. Moreover, chasing or touching a turtle can stress it and disrupt normal behaviors like feeding or breathing. Patience and calm observation let divers see authentic marine life in action. In our video, the turtle ignored the divers because they followed these guidelines.

When photographing a sea turtle, approach only as close as the turtle allows. In our video, our dive master used a long selfie stick. Also, we used a zoom feature when editing to get super close-up shots.

Identifying the Hawksbill Sea Turtle

The sea turtle in this video is a Hawksbill. Its scientific name is Eretmochelys imbricata. It has a hooked beak and two pairs of small scales between its eyes. These four scales are clearly visible when the turtle looks directly into the camera. The overlapping shell plates give the rear edge a jagged look. Each front flipper has two visible claws. Hawksbills in the Indo-Pacific grow to about one meter long and take decades to reach maturity.

Hawksbills feed mainly on sponges but also eat tunicates, soft corals, jellyfish, crabs, squid, and small fish. In the video, the turtle searched carefully under coral for food. Its slow, deliberate movements show it was comfortable and undisturbed by divers.

Conservation Status

Eretmochelys imbricata is critically endangered. It is illegal to harm, capture, or trade Hawksbill sea turtles or their shells. Plastic pollution is a major threat because turtles may mistake bags for jellyfish. Observing turtles responsibly helps them conserve energy and continue natural behaviors.

Hawksbill encounters are best when patience and respect guide the dive. When divers follow proper etiquette, turtles can feed and move freely without disturbance. To see a Hawksbill sea turtle behaving naturally on 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.

Winged Pipefish juvenile emerges from hiding

Posted on October 30, 2025 by Miguel's Diving • 0 Comments

Winged Pipefish are rarely seen. So, imagine our surprise to find a juvenile, complete with its distinctive wings!

Coming a Coral Wall

Miguel’s Diving staff work diligently to discover the hidden secrets of Gorontalo’s coral-rich dive sites. The dense hard coral environment provides many places for rare marine life to hide. This makes them hard to find.

Yet one day, staff discovered a juvenile Winged Pipefish. It was hiding among clumps of Halimeda coralline algae. This green algae has flat, round discs. As they age and die, the green surface peels away, leaving a brilliant white skeleton. After being crushed by waves, it becomes white sand. Underwater, the contrast between dark green and bright white makes a perfect place for pipefish to hide.

Unfortunately, no macro photographers were on board on the day of discovery. So, the crew returned to the site the following day to make some photos and this video. Gorontalo’s direct sunlight made shooting quite a challenge since the Winged Pipefish floated out of dark corners to over-lit sand and algae patches.

Distinctives of Winged Pipefish

Its scientific name is Halicampus macrorhynchus because of its long nose. Other common names include Ornate or Whiskered Pipefish.

One main distinctive is fleshy growths on its body. Notice the eight to ten pairs of skin flaps along the body. As the pipefish matures, these begin to disappear. Also, its long nose and face have these growths. In fact, these growths can make the face hard to see. The body color varies greatly but usually shows white spots along its back.

Like other pipefish and seahorses, the Winged Pipefish male will brood eggs in a ventral pouch. Divers report seeing this species in Bali, Sulawesi, and Raja Ampat.

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

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.

Risso’s Dolphins Sunbathe and Play

Posted on March 11, 2025 by Miguel's Diving • 0 Comments

Risso’s Dolphins thrive in the deep waters off Gorontalo’s southern shores. One day, we spotted a large, active pod. Using a drone, we watched as they sunbathed, played, and possibly mated.

Ghostly Apparitions

Risso’s Dolphins (Grampus griseus) are a distinctive species of dolphin. They are born gray but become whiter with age. The older one is, the whiter it appears. When passing under the dive boat or swimming nearby, they look like ghostly apparitions.

Their bodies also show visible scarring. Most scars come from fights with other Risso’s Dolphins, while other scars come from bites of deep-sea squid, their main diet. These features make them easy to identify.

Unlike other dolphins, Risso’s have rounded heads and no beak. They also have a crease running from the blowhole down to the upper lip. This unique feature is only visible up close or from a drone’s view.

Drone Video of Risso’s Dolphins

One day, our dive boat was heading to the second dive site when our captain spotted a pod of Risso’s Dolphins. They were sunbathing on the ocean’s surface, which is typical behavior in Gorontalo. Their distinctive white bodies confirmed their identity.

As we watched from a safe distance, one of our Indonesian guests launched his drone. Dr. Reyhan Aditya captured dramatic footage of this large pod. Some dolphins rested on the surface, while others played. One sequence even suggests mating behavior.

Risso’s Dolphins typically grow to three to four meters long and weigh between 300 and 500 kilograms. Clearly, most dolphins in this pod were adults. At other times, we have seen baby Risso’s among them. Usually, we see pods of about ten individuals, but this pod was much larger.

Worldwide Sightings

Risso’s Dolphins live in temperate and tropical oceans worldwide. They prefer deep offshore waters. Sometimes, they swim closer to land or oceanic islands when the continental shelf is narrow. This is true of Gorontalo’s southern coastline. Here, the continental wall of Sulawesi lies just a few meters from shore, plunging to four kilometers deep. This unique geography makes Gorontalo a great place for pelagic encounters.

Antoine Risso, a French naturalist, first described this species in 1812. Later, the dolphin was named in his honor.

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

Redlined Jorunna Love Triangle

Posted on February 9, 2025 by Miguel's Diving • 0 Comments

Redlined Jorunna nudibranchs made a rare appearance in Gorontalo. During the required safety stop, divers hovered over a patch of sandy rubble as they rested for three minutes. Looking at the sandy bottom, they discovered a cluster of black Long-spined sea urchins, several shy pipefish, and sea stars. Then, in the gentle surge, they noticed a moving, intertwined mass. It was three Redlined Jorunna nudibranchs engaged in group mating!

Love among Redlined Jorunna

Like other nudibranchs, this species is hermaphroditic. This means each nudibranch has both male and female reproductive organs. To fertilize the eggs, sperm must come from another individual.

It seems the three Redlined Jorunna we saw were donating sperm to each other. Nearby, divers noticed a pinkish ribbon of eggs already laid. According to scientific observers, this nudibranch species only appears in the open during mating. Otherwise, they hide in the reef.

Red lines and Fur

The scientific name for this species is Jorunna rubescens because of its reddish lines and markings. Underwater, divers can use additional light to bring out the reddish color.
Like other dorid nudibranchs, Redlined Jorunna have twin rhinophores on their heads and a bushy tuft of gills at the tail. These three parts can be pulled inside the body when the creature feels threatened.

Unique to dorids, fur-like caryophyllidia cover the body of Jorunna rubescens. Tiny spine-like spicules surround these sensory tubercles. Together, they give the body of this nudibranch a velvety appearance. As a result, some observers commonly call this species the Pink Furry Nudibranch.

For additional underwater photographs of Jorunna rubescens, including close-ups of the caryophyllidia, open this link.

Life and Environment

One of the larger dorid nudibranch species, Redlined Jorunna can grow up to 15 centimeters in length. The largest of the three we saw measured about nine centimeters. Jorunna rubescens lives on the seafloor in Indo-Pacific waters, including areas of coral reef and sandy or rocky bottoms like those found we found. For your chance to see unusual marine life in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Alligator pipefish hunts for lunch

Posted on January 21, 2025 by Miguel's Diving • 0 Comments

Alligator pipefish are rarely seen, despite their size. Even more remarkable is to follow one as it searches for something to eat. Yet that happened one day in Gorontalo – and we have the video to prove it!

A Mangrove Seed or a Blade of Grass

The Alligator pipefish (Syngnathoides biaculeatus) has a long, slender body that mimics a blade of seagrass. Some divers could also mistake it for a floating seed of a mangrove tree. Its body is usually green or brown. This camouflage helps it blend into its habitats. These include seagrass beds, mangroves, and estuaries. Predators and divers have difficulty recognizing one, even though it can grow quite large – up to 50 centimeters in length!

Most pipefish have paddle-like tails. But not Syngnathoides biaculeatus. Its body tapers to a point. That earns it the common name “Double-Ended Pipefish.” However, most divers call it the Alligator or Crocodile pipefish. Although it lacks a true prehensile tail like seahorses, it can bend its tail to form a hook. This allows the fish to hook onto something on the sea floor and remain motionless.

One Hungry Alligator Pipefish

One day in Gorontalo, we made our safety stop in a sandy area. Suddenly, one of our dive masters waved excitedly. He pointed to something floating motionless above the sand. It was an adult Alligator pipefish, measuring about 20 centimeters. While other divers relaxed and lunched above in our dive boat, we grabbed a video camera and followed the pipefish around.

The pipefish ignored us as it slowly surveyed the area. Soon, we noticed it was actually searching for something to eat. First, it swam across the seagrass bed, then among some coral boulders, and finally among clumps of dead Turbinweed. With the noonday sun beating down, it finally spied something to eat.

Syngnathoides biaculeatus Inhales its Food

The Alligator pipefish uses its elongated snout to suck in tiny prey. It likes to eat mysid shrimp and copepods. While on the hunt, a pipefish moves slowly through the water, probing and looking. When it spots prey, it quickly sucks it into its snout with a powerful vacuum-like motion. We caught all of this in our video.

Although we have seen this pipefish since the initial encounter, we cannot know how long it will stay. 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.