Maratua (also written Merah Tua), about an hour from Sangalaki by boat, is a large island with a massive lagoon. The island only rims part of the lagoon, the rest is fringed by reefs with two small islands in the south.
Most of the dive sites of Maratua are on the north-eastern side of the island. Diving here you can encounter turtles, napoleon wrasses, sting rays and eagle rays, sometimes reef sharks and leopard sharks. Most sites are steep slopes with patches of sand where rays or whitetips may be discovered. Coral growth is not very spectacular.
Maratua has several impressive drop-offs and you will have a good chance to sea large pelagics like sharks, tuna, eagle rays and schools of barracudas, trevally and mackerels.
On the island there are several villages so some of the reefs are quite heavily fished.