Hamelin Island lies in Hamelin Bay and once carried a light station (built 1937 and moved to the mainland in 1967 as the Foul Bay Lighthouse). Marinelife.org.au describes a sheltered reef flat on the lee side in about 9 m, with ledges and small caves, and a long list of fish: prettyfish, bullseyes, pullers, buffalo bream, old wives, herring, pike, foxfish, leatherjackets, moonlighters and wrasse, along with gorgonian sea fans and colourful sponges.

That diversity in shallow, sheltered water makes Hamelin Island one of the better reef dives in the bay. The ledges and small caves shelter fish and invertebrates, and the gorgonians and sponges add colour. The NE Bommie off the island (listed separately) offers a slightly deeper alternative.

It suits Open Water divers with access to a small boat, and snorkellers on calm days. The main challenge is getting there: the Hamelin Bay ramp is narrow and swell-exposed, and conditions in the bay change quickly when the wind turns north-west.

Hamelin Bay was a timber port from the 1880s, when a jetty built in 1882 and extended in 1898 served M. C. Davies' milling operations. It was notorious for wrecks in bad weather because it is exposed to the north-west gales of winter storms; the 22 July 1900 storm alone wrecked several ships, and only the old jetty piles remain today. The bay is now a recreation zone in the Ngari Capes Marine Park, and every wreck in it older than 75 years is protected. Anchor on sand, never on the reef.

Hamelin Bay is on the coast west of Karridale, about 35 km south of Margaret River and 30 km north of Augusta, reached via Caves Road and Hamelin Bay Road. Park at the boat ramp/jetty area beside the Hamelin Bay Holiday Park. Launch at the Hamelin Bay boat ramp - marinelife.org.au warns it is narrow, slippery and swell-exposed, and a 4WD may be needed.

Run out to Hamelin Island (a short boat trip from the ramp) and anchor on the sheltered lee side.

The lee side is sheltered from the prevailing swell, but getting there requires a calm day and the ramp is swell-exposed. Summer easterly mornings are best. General pattern on the Capes and Leeuwin coast: summer mornings often have light easterly (offshore) winds before a south-westerly sea breeze, and long-period south-westerly groundswell can arrive on otherwise calm days; winter fronts bring big swell and north-westerly winds.

Check the Bureau of Meteorology swell forecast, not just the wind.

Anchor in the lee, descend onto the reef flat and explore ledges and small caves at 6-9 m, then return to the anchor. Agree a turn pressure before descending (half gas, or a third where current is likely), carry a DSMB, and make a 3-minute safety stop at 5 m.

No operator; private boats. Nearest dive services: Swan Dive (Busselton/Port Geographe) for fills, hire, nitrox and charters; no dive shop in Margaret River or Augusta.