Kadavu Island is best known for the Great Astrolabe Reef that runs along its southern shore, and up passed Ono Island to the east. The reef (named after a French ship), is a breeding ground for big fish like tuna, marlin, GT and sharks. Gaps in the Reef, like Naiqoro Passage, see big fish action along their colourful soft coral coated walls and are also subject to currents.
Buliya Island, north of Ono Island, is famous for its manta ray snorkeling.