The Clam Gardens in Watsons Bay is Lizard Island's signature snorkel site. Queensland Parks describes giant clams up to 2 m long among hard and soft corals, and the resort calls it extremely popular, noting many different species of clams. It lies in the middle of the bay and is reached by a short swim from the beach or by resort tender.

Giant clams are the largest bivalve molluscs on Earth, and several species occur here – from the true giant clam, Tridacna gigas, which can exceed a metre across and weigh hundreds of kilograms, to smaller species with brilliantly coloured mantles in blues, greens and purples. The colours come from symbiotic algae living in the mantle, which provide the clam with food through photosynthesis – which is why the clams sit in shallow, sunlit water. The clams share the reef with hard and soft corals and a variety of reef fish: parrotfish, butterflyfish, damselfish, wrasse and anemonefish.

Turtles are sometimes seen in the bay. The site is shallow, so snorkellers can see the clams clearly from the surface, and duck-diving brings you face to face with them. Queensland Parks recommends snorkelling at high tide, when there is more water over the reef, entering from the southern end of the beach.

The Lizard Island Research Station, operated by the Australian Museum, has long studied giant clams, and the Clam Gardens are an important reminder of how these animals, once heavily harvested across the Indo-Pacific, can thrive in protected areas. Visitors should never touch or stand on the clams, and should keep fins clear of the coral. For families and first-time snorkellers, this is one of the best reef experiences in Australia.

Lizard Island lies about 27 km off the Cape York coast and roughly 240 km north of Cairns. Most visitors fly: resort guests take the scheduled light-aircraft transfer from Cairns (about 1 hour) to the island airstrip, and campers can charter flights or arrive by private boat. There is no public ferry.

The dive and snorkel sites are reached by the Lizard Island Resort dive centre's boats (reserved for resort guests) or by liveaboards – Spirit of Freedom uses Lizard as the fly-in/fly-out changeover point for its 3- and 4-night trips, and Mike Ball's Spoilsport visits on Cairns-based expeditions. Campers at Watsons Bay must carry gear about 1.2 km from the airstrip and bring all supplies.

Lizard Island sits in the path of the south-east trade winds, which blow strongly (often 20–30 knots) from about April to September. The island's western and northern bays (Watsons Bay, Mermaid Cove, Anchor Bay) are sheltered, but open-water crossings to the outer ribbon reefs (Cod Hole, Dynamite Passage, No Name) can be rough and are cancelled in strong winds. October–December usually brings lighter winds and the clearest water; the wet season (December–April) brings northerly winds, storms, cyclone risk and marine stingers (November–May).

Tides are significant – shallow bay snorkelling (e.g. Clam Gardens) is best around high tide. Visibility around the island is typically 10–20 m; the outer ribbon reefs often exceed 25 m.

At high tide, swim out from the southern end of the beach to the clam beds, snorkel slowly over them at the surface or duck-dive to 2–4 m, and keep a respectful distance. Return to the beach the same way before the tide drops.

Lizard Island Resort – guided local snorkel tours and Hike & Snorkel tours (guests only), several times a week; independent snorkellers from the camping ground and anchored yachts.