Gato Island has around five separate dive sites and is a fantastic dive area for a number of reasons. The island is a marine reserve and a sanctuary to sea snakes. This provides a great environment for a large diversity of different types of marine life. The site is also a great place for underwater photography as it provides opportunities for both macro photos as well as big fish and panoramic shots.

One of the most famous formations is a unique underwater tunnel that runs through the island for about 25 metres. This can only be completed by advanced divers and dive torches are needed as part of the dive is cut off from external light. The tunnel is covered with sponges and soft corals. The tunnel is at around 12 metres and the dive then descends to about 30 metres to the sea floor. Visibility is usually around 15 metres.

The coral on the island is in good condition and there are many swim throughs, overhangs, and different types of rock formation. There are many soft corals with many different colours and these provide shelter for many nudibranchs, sea horses, and frogfish. Divers are likely to also find many banded sea snakes, mantis shrimp, porcupine fish, scorpion fish, seahorses, and cuttlefish. Out in the ocean further out, there are often schools of mackerel and large schools of squid. The site is also a home to many cat sharks and bamboo sharks. The crevices are perfect places for white tip reef sharks to rest and it is almost guaranteed that divers will spot some on the dive.