There are several diving terrains ranging from walls to caverns and fringing reefs. The island is also popular with green turtles that use it as a breeding ground laying their eggs in the night time. With 9 dive sites around Derawan,  there are diversity of marine life,  such as white tip, leopard and nurse sharks, cuttlefish, Spanish mackerel, jacks, batfish and ornamental reef fish in varied terrain, huge lavender seafans, cuttlefish, nudibranchs galore, unusal tube anemones, blue ribbon eels and multi colored crinoids.  A completely new species of coral is also found here named appropriately Acropora Derawanensis. Derawan's 656ft jetty is home to dumpling squids, crocodile fish, finger-sized purple crayfish, squat lobsters, decorator crabs, sea horses and various species of worms, tunicates and Dwarf scorpionfish. Shallow (10 metres) reef at Sea Garden is very healthy coral and abundance of  flatworms and nudibranchs, ribbon eels, large blennies and anemones.

Kakaban island lies around 20 minutes from Sangalaki and offers 2 very different diving experiences. In addition to some spectacular wall diving, where pelagics can be found.

The island of Kakaban is an isolated marine lake (lagoon) and unique in its own.  Thousands of years ago the island was naturally uplifted and then isolate the marine ecosystem from surrounding marine area making all biota in this marine lake become very unique and endemic critters such as non-stinging jellyfishes and non-stinging anemone.  Marine biologists have also found a number of unknown species of anemones, tunicates and crustaceans in the lake. The shoreline is fringed with a tangle of mangroves. Their sturdy roots are carpeted with sponges, seaweeds and tunicates. Visibility is around 10-12 meters and at its deepest point the lake is 18 meters with tidal amplitude of about 0.2m, this is a result of a network of underground fissures that connect to the ocean. This truly is a biological paradise.

Sangalaki is known all over the world as the center of Manta Rays. Some of them are giant and gorgeous ray that have wing span up to 3 meters wide. To the east of the island are Manta Avenue, Manta Parade and Manta Run - where the manta rays can be found feeding, gills wide open, on a rich supply of plankton minutes from the beach. The mantas can sometimes be seen cruising down these manta highways, whilst other rays forage around for food under the sand together with the goatfish. Their wing tips break the surface at regular intervals as they circle around you. They prefer to swim close to the surface, so snorkeling or free diving is also a good way to interact with them. The best time to see them seems to be full moon when there might be as much 20 mantas hovering over the cleaning stations.  Gently sloping patch reef frequented by manta rays. These giants, some with wing spans as great as 3.5 metres, fly in graceful circles while feeding in the current line, so they can be seen up close by snorkellers as well as divers.

There are several impressive drop offs and a great drift dive can be done through the channel into the lagoon. The channel entrance is at 27 meters and strong currents sweep by attracting large pelagics such as eagle rays, mantas, barracuda, tuna, mackerel, mantas, hammerheads, and variety of sharks. It is the home of the barracudas. Best time to dive the channel is on an incoming or slack tide where marine life reaches a crescendo of activity. Coral growth is not as spectacular here due to the strong currents, diving should also be carefully planned. The island is inhabited hence unfortunately some of the reefs have been fished.

Samama  island is very close to Sangalaki and Kakaban. It has been described as an underwater naturalists dream teeming with macro life. It offers the unique scenery of bio-diversity for divers to interact with. Since the waters surrounding Samama are shallow and ideal for beginners and u/w photographers looking to capture the magical undersea lighting. Large swathes of colourful soft corals and sponges intermingled with hydroids and sea whips give way to massive cabbage, staghorn and plate coral colonies. Around the edges of the sand patches iridescent blue ribbon eels can be seen along with many juvenile fish that take shelter in the islands mangrove root system labyrinths. Pygmy seahorses have been found here and there are myriad nudibranchs to be discovered.