At first glance, the idea sounds almost impossible. A lake in the middle of the ocean, filled with jellyfish that do not sting.
Yet that is exactly what you will find at Kakaban Jellyfish Lake, located in the Derawan Archipelago.
This unusual ecosystem has fascinated scientists and travelers alike. The lake sits on top of Kakaban Island, surrounded by the sea, but completely separated from it. Inside the lake lives a population of jellyfish that have evolved in isolation for thousands of years.
Understanding how Kakaban Jellyfish Lake formed and why its jellyfish do not sting reveals just how extraordinary this place truly is.
Kakaban Jellyfish Lake is what scientists call a marine lake. These lakes were formed thousands of years ago when sea levels changed and parts of the ocean became trapped inside islands.
Over time, the connection between the sea and the lake closed or became extremely limited. The water remained saltwater, but the ecosystem inside began to evolve independently.
Kakaban Island itself is a raised coral island. As geological movements lifted the reef above sea level, seawater became trapped inside natural depressions. This created a lagoon that slowly transformed into the lake we see today.
Even though Kakaban Jellyfish Lake is surrounded by the ocean, it is now an isolated world with its own environmental balance.
The jellyfish inside Kakaban Jellyfish Lake belong mostly to species of golden jellyfish and moon jellyfish. Normally, these animals use stinging cells to catch prey and defend themselves.
But inside the lake, things evolved differently.
Because there are almost no natural predators and very little competition for food, the jellyfish gradually lost the need for strong stinging cells. Over thousands of years, their stings became extremely weak.
For visitors swimming in the lake, this means the jellyfish feel harmless. Most people do not feel any sting at all.
This unusual evolutionary path is what makes Kakaban Jellyfish Lake so special.
Marine lakes like Kakaban are incredibly rare. Scientists estimate that there are only a handful of jellyfish lakes like this in the world.
The most famous examples are found in:
Each lake has its own species and unique ecological conditions.
Kakaban Jellyfish Lake is considered one of the largest and most accessible of these ecosystems, which makes it an important natural site for research and conservation.
Visitors can reach Kakaban Island by boat from the surrounding islands of the Derawan Archipelago. After arriving, a short wooden walkway leads up through the forest and down to the lake.
Stepping onto the viewing platform and seeing thousands of jellyfish drifting silently through the water is a moment many travelers remember for years.
Swimming among them is an experience unlike anything else in the ocean. Instead of avoiding jellyfish, you move gently among them as they pulse slowly through the water.
Because the ecosystem is extremely fragile, visitors are asked to follow simple rules to protect it. Touching the jellyfish, wearing sunscreen in the lake, or disturbing the animals is discouraged to keep the habitat healthy.
Many travelers exploring the Derawan Archipelago choose to include Kakaban in their itinerary.
The island is often visited as part of day trips that combine several iconic locations in the region.
Guests staying with Scuba Junkie Sangalaki regularly explore Kakaban alongside other nearby highlights such as manta cleaning stations, vibrant coral reefs, and turtle-rich dive sites.
Combining diving with unique natural experiences like Kakaban Jellyfish Lake gives visitors a deeper appreciation for the diversity of the Derawan Archipelago.
Kakaban Jellyfish Lake is more than a beautiful place. It is a reminder of how isolated ecosystems can evolve in surprising ways.
The jellyfish living here have adapted to their environment over thousands of years. Protecting this fragile ecosystem ensures that future generations will also have the chance to witness it.
When visiting places like Kakaban, responsible tourism plays an important role. Respectful swimming, careful movement in the water, and following local guidelines all help preserve the lake.
The idea of a lake in the middle of the ocean filled with jellyfish that do not sting sounds almost like a myth. Yet Kakaban Jellyfish Lake proves that nature still holds many surprises.
For travelers exploring the Derawan Archipelago, visiting this unique marine lake offers a chance to experience one of the rarest ecosystems on Earth.
And sometimes the most memorable moments of a trip happen not only underwater with dive gear, but floating quietly in a lake surrounded by thousands of gentle jellyfish.
Many divers arrive dreaming of manta rays, turtles, or passing pelagics—yet one of the most captivating reef creatures is often much smaller and far more mysterious. Cuttlefish in Derawan can steal the show during any dive, surprising guests with their intelligence, colour-changing tricks, and gentle, curious nature.
This guide gives you a deeper understanding of these remarkable cephalopods, what behaviors you might see, and how to enjoy respectful encounters that protect both the animal and your experience. No dramatization, no exaggeration—just a closer look at a creature that makes Derawan’s reefs even more special.
Cuttlefish are famous for their ability to change colour, texture, and pattern in a split second. They can blend into coral rubble, become striped, spotted, smooth, or spiky, and even mimic other animals. Watching cuttlefish in Derawan shift patterns feels like witnessing underwater magic—but it’s pure biology. Their skin contains chromatophores and papillae controlled by muscles, all working instantly to match their surroundings.
Cuttlefish often hover calmly, letting divers approach slowly as long as they feel unthreatened. Common behaviours include:
Nothing exaggerated—just small, genuine behaviours that fascinate divers.
Derawan’s combination of healthy corals, sheltered bays, sandy patches, and rich biodiversity creates an excellent environment for cuttlefish. Good habitat equals good sightings, and many divers enjoy frequent encounters without overcrowded conditions.
Cuttlefish often rest or hunt around sandy bottoms near coral outcrops. These gentle slopes and calm areas offer camouflage opportunities and easy access to prey. While we can never guarantee sightings, these habitats increase your chances.
Cuttlefish are wonderfully active at dusk and during night dives. Their colours appear more vibrant under torchlight (used respectfully), and you may spot juveniles or adults hunting. As always, avoid shining lights directly into their eyes.
Although cuttlefish sometimes seem calm and approachable, they’re sensitive animals. A respectful distance allows you to observe natural behaviour without causing stress. Signs of discomfort include colour flashing, backwards swimming, or lifting the tentacles defensively.
Good photos come from patience, not pressure. Avoid chasing or cornering the animal. Use red light when possible, keep flash use minimal, and never block the cuttlefish’s escape route. Responsible habits allow future divers to enjoy equally peaceful encounters.
Sometimes divers may spot clusters of grape-like eggs tucked under ledges. These develop into tiny juvenile cuttlefish—perfectly formed miniature versions of adults. Observing them should always be done at a respectful distance, with no touching or disturbing the structure around them.
During mating seasons, males may show intense patterns to attract females or ward off rivals. These displays are subtle but fascinating—a reef storyline happening quietly while divers drift past.
Derawan is known for mantas, turtles, and vibrant coral reefs, but cuttlefish add a layer of gentle wonder to the experience. Their intelligence, calm behaviour, and unique camouflage make them unforgettable for both new and experienced divers.
Cuttlefish in Derawan remind us that not all remarkable encounters are big or dramatic. Sometimes, the most memorable moments come from observing small details and quiet reef life.
No. They are generally shy and avoid conflict. Respectful distance ensures a calm interaction.
They can be spotted year-round, though behaviours vary—night dives and dusk are often great times.
They can if severely provoked, but divers who maintain proper distance have nothing to worry about.
Stay far enough away that the animal doesn’t change behaviour. If it starts flashing colours or retreating, you’re too close.
Yes, occasionally. Eggs look like small white or translucent grapes tucked under ledges.
Very. They are known for problem-solving abilities and complex communication patterns.
Cuttlefish may not be the headline act on every dive itinerary, but they offer something rare—quiet beauty, fascinating behaviour, and memorable encounters that stay with you long after your trip. With careful, respectful diving, you’ll discover just how special cuttlefish in Derawan truly are.
Look closely, move slowly, and enjoy the reef’s understated wonders.
Leopard sharks in Derawan.
It’s a leopard… but underwater. 🐆🌊
With spots instead of stripes, elegance instead of speed, and a calm confidence that turns every encounter into a moment of awe, the leopard shark is one of the ocean’s most underrated beauties. Divers who have been lucky enough to see one know: it’s the kind of sight that makes your heart skip a beat, then slow down as you realize you’re sharing space with one of the sea’s most graceful predators.
But that’s just the beginning. The Derawan Archipelago is home to several species of sharks, each playing a vital role in keeping the reef healthy. Before we meet them, let’s get to know the spotted star of the show.
Despite its name, the leopard shark (Stegostoma tigrinum), also known as the zebra shark, is not related to the big cat—but it does have the same quiet power and unmistakable markings. When young, these sharks wear black-and-white stripes like a zebra. As they mature, the stripes fade into beautiful spots, earning them their leopard-like name.
They belong to the carpet shark family, a group known for bottom-dwelling species that love lounging on sandy seabeds and weaving through coral gardens.
Leopard sharks are found throughout the Indo-Pacific, from eastern Africa to northern Australia, often seen resting on the seafloor during the day and becoming more active at night.
They’re not hunters in the dramatic sense; instead, they glide slowly close to the sand, searching for food. Their diet includes crustaceans, small bony fish, mollusks, and sea snakes. Using their flexible bodies, they can twist and reach into small holes in the reef where prey hides.
In the Derawan Archipelago, their favorite hangouts are sandy channels and shallow reef plateaus—places where they can rest between feeding sessions.
Every encounter with sharks in Derawan feels like meeting a one-of-a-kind masterpiece.
Not at all. In fact, they’re among the calmest and most docile sharks in the ocean. Divers often find them lying motionless on the seabed, unfazed by bubbles or gentle camera flashes (always from a respectful distance, of course).
Leopard sharks are curious but shy; if they swim away, it’s never in panic—just a quiet glide into the blue. Their gentle nature makes them perfect ambassadors for shark conservation, breaking stereotypes that all sharks are dangerous.
Leopard sharks may steal the spotlight, but they share these waters with an impressive supporting cast.
The Derawan Archipelago hosts a healthy variety of sharks—proof that the ecosystem here still thrives:
Each of these species plays a unique role in keeping the ecosystem balanced—controlling fish populations, cleaning the reef, sharks in Derawan reminding us how vital they are to a healthy ocean.
Across the world, sharks are disappearing at an alarming rate. Overfishing, finning, and habitat destruction have led to steep declines, with many species losing more than 70% of their population in the past 50 years.
Yet sharks are the pulse of the ocean. As apex or mid-level predators, they regulate fish populations and remove the weak and sick, keeping the reef balanced. Without them, coral ecosystems collapse.
In the Derawan Archipelago, their presence is a sign of hope—a living indicator that this corner of the Coral Triangle still beats strong.
By diving responsibly, refusing shark fin products, and supporting marine conservation, we help keep that pulse alive.
At Scuba Junkie Sangalaki, island life feels calm and timeless—the rhythm of waves, turtles in the shallows, and laughter from the dive deck. But the moment you roll into the water, the magic multiplies.
Below the surface, the reef reveals its quiet residents: the leopard shark sleeping in the sand, a white tip cruising past, a curious black tip circling in the distance. Each dive is a reminder that you’re entering a world that’s wild, vital, and worth protecting.
We believe that every diver can be part of shark conservation simply by witnessing their beauty and sharing respect for them. Because the more people see sharks for what they really are—not monsters, but miracles—the safer their future becomes.
Which one of the sharks in Derawan would you love to meet underwater?
Tell us in the comments—and help spread the word that these incredible animals deserve admiration, not fear.
The Derawan Archipelago is more than just a diving destination — it’s a biodiversity hotspot pulsing with fascinating marine life. This second part of our marine encounters series takes a deeper dive into what makes this region so special: the animal behaviors, research efforts, and underwater moments that elevate diving here into something unforgettable.
From manta rays and whale sharks to hidden critters and baby sharks, this is where adventure meets insight.
One of the most fascinating marine life in the Derawan Archipelago is the manta ray. These filter-feeding giants glide through the shallows around Sangalaki Island and beyond, feeding on plankton and occasionally stopping at cleaning stations where smaller fish nibble away parasites from their bodies.
But here’s where it gets nerdy (and cool): each manta ray has a unique set of spots on the underside of its body — permanent patterns that scientists use like fingerprints to track individuals. Researchers from the Marine Megafauna Foundation (MMF) are currently working in Derawan to study these rays using photo-identification techniques.
Each photograph helps scientists monitor behavior, movement, and habitat use across the region. This research is vital in protecting mantas from threats like overfishing and habitat degradation.
📖 Want to learn more? Visit MMF’s Manta Ray Research page
The whale shark (Rhincodon typus) is the largest fish in the ocean, reaching lengths of up to 12 meters. Despite their size, these gentle giants are completely harmless to humans — filter-feeding on plankton, small fish, and shrimp by sucking in water and straining food through their gill rakers.
In the Derawan Archipelago, whale sharks are often spotted near local fishing platforms where they gather to snack on baitfish. While these tours aren’t part of our dive trips, they are operated by local fishermen and can be arranged once you’re on Derawan Island, depending on season and conditions.
These animals are migratory and long-lived — and sadly, they’re listed as Endangered by the IUCN. Protecting them means understanding where they go, how they live, and how human activities impact them.
Diving in the Derawan Archipelago means you’re in for diverse shark encounters. Each island has something unique:
But one of the most meaningful sights? Juvenile sharks cruising in protected, shallow bays. These areas are what we call shark nurseries — coastal environments where young sharks can grow safely.
A nursery is defined by three main criteria:
By diving respectfully in these areas, we help safeguard the future of sharks — one juvenile at a time.
Macro diving is all about finding small fascinating marine life, often camouflaged marine life that’s easy to miss if you’re not looking closely. It’s about tuning in to the reef and discovering the richness within each square meter.
Derawan Island is one of the best places in Indonesia for macro diving. From cephalopods to flatworms, tiny shrimp, and colorful nudibranchs — the reef here holds secrets that even experienced divers miss at first glance.
Nudibranchs, for example, are soft-bodied sea slugs that breathe through external gills. Many have evolved to showcase bold colors and patterns to warn predators of their toxicity. Their incredible variety (over 3,000 species known!) makes them a favorite among underwater photographers.
Our dive guides are trained to spot the smallest movement or shape change — but the real joy is when you find something. Macro diving is part observation, part puzzle-solving — and entirely addictive.
Turtles are everywhere in the Derawan Archipelago. From green turtles (Chelonia mydas) to the critically endangered hawksbills (Eretmochelys imbricata), these ancient mariners are a near-daily sight during dives, often resting on coral, grazing on seagrass, or swimming beside you in the blue.
We’ve teamed up with the Marine Megafauna Foundation to start building a turtle photo-ID database. Each turtle can be identified by the unique pattern of facial scales — just like a fingerprint.
Guests are invited to participate by submitting clear, side-profile photos taken during their dives. This helps researchers monitor turtle populations, track their movements, and understand how best to protect them from threats like marine debris, fishing nets, and habitat loss.
Why it matters:
💡 Tip: Always keep at least 3 meters of distance, never chase or touch, and let them approach you on their own.
One of the most endearing sights in Derawan happens right at the water’s edge. At sunset, our team leads gentle shoreline walks where you might spot baby guitar sharks (family Rhinobatidae) swimming just meters from the beach.
Why are they there? These shallow, warm waters offer a safe haven from larger predators, an abundance of crustaceans to feed on, and a quiet space to grow.
Guitar sharks are a unique evolutionary blend of sharks and rays — with flattened heads, ray-like bodies, and shark-like tails. They’re critically endangered, making each sighting not only memorable but meaningful for conservation.
The fascinating marine life of the Derawan Archipelago isn’t just something to admire — it’s something to understand. From behavior to biology, from feeding to breeding, the more we know, the better we protect.
Join us in exploring — and learning from — the reefs of Derawan. Whether it’s contributing photos to science or spotting something new on a night dive, your journey here matters.
