Little Salmon Bay is the sheltered lagoon that makes Rottnest's south coast so popular with snorkellers. SeaLink describes it as a sheltered lagoon with calm waters and a story-filled snorkel trail, ideal for families and beginners, with brightly coloured tropical fish. It lies immediately west of Parker Point, and together with the Parker Point trail and Salmon Bay it forms the core of the island's warm-water snorkelling area.

The Rottnest Island Authority's warm-water guide notes that the Salmon Bay and Parker Point area supports about 135 species of tropical fish, including wrasse, dusky morwong and schools of black bream, with cauliflower, brain, branching and plate corals on the limestone. In Little Salmon Bay those corals grow as small bommies and patches in water only a few metres deep, so snorkellers can see them without diving down. Seagrass and kelp alternate with the reef.

The bay suits families, first-time snorkellers and relaxed scuba divers wanting a long, shallow shore dive. It is protected enough to use in most winds, which makes it the default south-coast snorkel. Look but do not touch: the corals here are at the southern limit of their range and easily damaged by fins and feet.

Rottnest's south coast is where the warm Leeuwin Current has most influence, which is why the corals and tropical fish in these bays are unusual for a location so far south. The Rottnest Island Reserve bans spearguns and handspears across all island waters. The general rule is simple: in a northerly or easterly, snorkel the south side; in a southerly, go to the north-coast bays instead.

Cycle about 5-6 km south from the Thomson Bay settlement past Parker Point (about 20 minutes) or take the Island Explorer bus to the Parker Point/Little Salmon Bay stops. Bike racks sit above the bay and a short path leads to the beach. Enter from the sand into the sheltered lagoon.

Snorkel gear can be hired in the settlement; scuba divers must bring filled cylinders from Perth on the ferry, as there are no fills on the island.

SeaLink rates it suitable in north, north-east, east, south-east, south-west, west and north-west winds - almost everything except strong southerlies, which push swell into the bay. Summer water is warm thanks to the Leeuwin Current. Mornings are calmest and least crowded.

General pattern at Rottnest: summer brings calm morning easterlies followed by a strong south-westerly sea breeze from late morning, so dive early; winter brings north-westerly fronts and large swell, with clear, calm spells between them. Check the Bureau of Meteorology coastal forecast for swell height and period before committing.

Enter from the beach, snorkel the reef around the lagoon following the trail markers, and in calm conditions extend east toward Parker Point before returning to the beach. Snorkellers should stay within easy reach of the exit point and swim with a buddy; scuba divers at these depths need no safety stop but should ascend slowly and surface near the float.

No operator needed - self-guided snorkel/shore dive. Snorkel gear hire from Pedal & Flipper and other outlets in the Thomson Bay settlement; guided snorkel tours (Rottnest Snorkel) run from Thomson Bay. Scuba divers bring cylinders from Perth - no fills on the island.