Coffin Island is a small granite island lying just south of Two Peoples Bay, and a rare chance near Albany to dive with Australian sea lions. Marine Life Network describes rocky reefs with caves, gutters and sponge gardens, abundant marine life and colonies of both Australian sea lions and New Zealand fur seals, with sheltered areas for swimming with the seals.

The reef is typical outer-coast granite: large boulders and slabs broken by gutters and small caves, kelp on the tops and sponges, ascidians and gorgonians in the shaded walls. Blue groper, harlequin fish, boarfish, western blue devils and schools of sweep and bullseyes are common, with crayfish in the cracks. The main attraction is the pinnipeds – young sea lions and fur seals often investigate divers in the shallows, twisting around them and blowing bubbles.

Australian sea lions are an endangered species that breed only in WA and SA, and the south coast colonies are small; divers should never approach hauled-out animals, should let the seals come to them, and should keep clear of pups. The island is a nature reserve with no landing.

Access is the challenge. Most visitors use small private boats launched at Two Peoples Bay, from where the island is close, but the site is exposed to easterly weather and ocean swell. It rewards divers prepared to organise their own trip on a good day with an uncrowded site and memorable wildlife encounters. Carry oxygen and a first-aid kit on board: the nearest help is Albany, and recompression is in Perth.

From Albany take Lower King Road and Nanarup Road east, then turn onto Two Peoples Bay Road (about 35 km, 30-35 minutes). Launch at the small boat ramp beside the Two Peoples Bay visitor centre; Coffin Island is a short run (about 10-15 minutes) south out of the bay past Mount Gardner. Alternatively it is roughly 45-60 minutes by boat from Emu Point around Herald Point and Cape Vancouver in good weather.

Anchor in the lee of the island in sand; landing is not permitted (nature reserve).

Coffin Island is exposed to the open ocean on its southern and eastern sides. Dive the sheltered northern/western lee in south-westerly to westerly weather with swell under about 2 m; avoid it in easterlies and south-easterlies, which also make the Two Peoples Bay ramp uncomfortable. Autumn high-pressure systems give the best windows.

Anchor in the lee, descend to 10-15 m and follow the reef along the island, checking caves and gutters. Spend the last part of the dive in the shallows near the haul-out, where sea lions are most likely to join, and stay calm and passive to encourage interaction.

No regular operator; private boats and club trips. South Coast Diving Supplies may run it as a special charter.