Timor-Leste
A small volcanic island in the Wetar Strait about 23.5 km north of Dili, ringed by fringing reefs and steep drop-off walls; a 2016 Conservation International survey recorded the highest average reef-fish count per site...
Atauro Island lies in the Wetar Strait/Banda Sea north of Dili, within the Coral Triangle. The sheltered east coast near Beloi has gently sloping coral gardens, while the exposed west coast has dramatic drop-offs. A 2016 Conservation International survey recorded the highest number of reef fish species per site ever measured. Blue and sperm whales migrate past the north coast September-November. Two PADI dive resorts operate out of Beloi. Source: Conservation International survey (via ataurodiveresort.com), Wikipedia (Atauro).