The Great Astrolabe Reef is one of the largest barrier reefs in the world and encompasses Kadavu Island, Ono Island and other small islands within a natural protective lagoon. The reef is predominantly located along the southern coast of Kadavu Island and arks north around Ono Island and further north to Buliya.
The reef is a breeding ground for many large billfish (marlin) species, sharks, tuna, giant trevally, mahi-mahi (dolphinfish) and snapper, due to it having many channels leading from extremely deep water into shallow lagoons. Parts of the reef, such as Naiqoro Passage, one of the main passages, are protected from fishing and require entry fees. This is because Naiqoro Passage is one of the main thoroughfares for large fish.
The reef is a great location for experiencing marine life and coral diversity, being relatively unspoilt due to its distance from dense population. Buliya is famous for its manta ray snorkelling and is a highlight of travelling to Kadavu Island and Ono Island.
The water temperature varies from 25 to 32 degrees Celsius, making it ideal for snorkelling and scuba diving. The average visibility underwater is 25 metres, with visibility increasing to up to 40 metres on clear, windless days.
Resorts on Kadavu Island and Ono Island offer accommodation with direct access to snorkelling and diving.