Sangalaki is known for the large gatherings of manta rays that come here to feed on plankton. Most dives here are in shallow water, since the mantas feed near the surface. Visibility is somewhat restricted, specially during the rainy season. Sangalaki is surrounded by a shallow lagoon and the reefs start a distance out from the island, dropping from about 4m to 18 to 24m and up to 40m at some point. The island itself is a breeding ground for green turtles. At night female turtles come ashore and lay their eggs and small baby turtles can be seen regularly, when they hatch. The island and its surrounding reefs are protected as an Indonesian Marine Park.

Not just dive in Sangalaki, but you can find large groups of mantas, flipping and rolling all around you, but you can also snorkel in a freshwater lake which seems more like stingless jellyfish soup, and enjoy the splendid rugged wall dives of nearby Kakaban. Being at Sangalaki is like being in several great dive destinations at once - manta rays, macro, Jellyfish Lake and splendid wall dives, a winning combination.

The other dive of Sangalaki are worthwhile, as the coral are healthy, the currents are mild and visibility is stellar. There are huge groupers and bountiful reef fish at a bommie near corral garden. Stinfray patch is famous for regular sightings of blue-spotted rays, eagle rays and Manta.

Green turtles live, breed and lay eggs on several of the small island of the northeast coast of Kalimantan. If you lucky, you will find the tiny turtles hutch, tiger sharks, which preys on grown turtles, patrol the reef’s outer edge.

The manta rays are found in numbers as large as 50 at the dive sites found on the east coast, namely Manta Avenue, Manta Parade and Manta Run. Usually, you'll find these graceful mantas near the surface with their gills wide open as they feed on the rich plankton to be found in these waters. The mantas can also be found cruising the seas or less often foraging for sustenance down on the sandy sea beds.

Another highlight of Sangalaki diving is the site known as Jellyfish Lake on nearby Kakaban Island - the sight of thousands of jellyfish floating around you has an almost other-worldly beauty to it, and you need have no fear of stings while snorkelling here (you can't dive in the lake). There are four different varieties of jellyfish in the lake situated in the middle of the island. With no access to the open sea, the jellyfish here have had no encounters with their natural predators and as a result have lost their sting.