Maratua Atoll: The lagoon of Maratua is connected to the open sea by a narrow channel. The tides cause strong currents and therefore attract sharks, eagle rays, schools of jacks and barracudas, reef sharks and occasionally even hammerhead sharks.
Kakaban: Barracudas and mackerel can often be seen on the steep sides of Kakaban. In the interior of the island is a large salt water lake that contains vast quantities of harmless jellyfish (the tentacles don't have any poison).
Sangalaki: Sangalaki is world famous for its manta rays. Mantas can be seen nearly the whole year round. Encounters with these elegant animals make it an unforgettable experience for any diver.
The best time for diving the reefs off East Kalimantan is from April through to December. Water temperatures range from 19C to 30C (66F-86F) with a year round average of 28C (82F). Visibility ranges from 10-80m (32ft-260ft).