Indian Ocean Territories dive sites

Thundercliff Cave is one of Christmas Island's signature dive sites, consisting of two interconnected sea caves. The main chamber is entered at around 6 metres depth through a wide entrance that floods the interior with stunning blue light. The sandy floor descends to about 22 metres, and the cave is large enough that ambient light from the entrance illuminates most of the interior. A second, smaller cave connects to the first and offers a more enclosed atmosphere. No cave diving certification is required as the caves have large openings and clear exit routes.

Whale sharks visit Christmas Island's waters from approximately November to April, with peak sightings from December to March coinciding with the annual red crab spawning. As billions of red crab larvae wash into the sea, they create a massive plankton event that attracts whale sharks, manta rays, and other filter feeders. Christmas Island offers a less commercialised whale shark experience than Western Australia's Ningaloo, with fewer boats and divers in the water.

Christmas Island is an Australian external territory in the Indian Ocean, approximately 2,600 kilometres northwest of Perth and 350 kilometres south of Jakarta. Flights operate from Perth several times weekly, with a flight time of approximately 3.5 hours. The island has one dive operator, Extra Divers, based in Flying Fish Cove. With only about 1,800 residents and very few tourists, diving at Christmas Island is an uncrowded and pristine experience.