The Blowhole is one of the most remote and rewarding shore dives on the Fleurieu, if you can get there and catch the right day. The site lies at Blowhole Beach in Deep Creek Conservation Park, on the southern coast of the peninsula facing Backstairs Passage and Kangaroo Island. The Scuba Divers Federation describes it as a beautiful unspoilt site, teeming with life, reached only by four-wheel drive through the park and a steep track, then a walk of several hundred metres.

Because so few people make the effort, marine life is abundant: sources mention crayfish galore, seals and seadragons. The coast is rocky with reef, kelp and boulders, and the clean water from Backstairs Passage gives better visibility than the gulf sites. Expect blue groper, harlequin fish, sweep, magpie perch, wrasse and leatherjackets, along with abalone and urchins on the rocks.

The same exposure that keeps the water clean makes the site dangerous. The Federation warns of heavy current and freak waves, and strongly advises diving with someone who knows the area. Waves can surge up the beach unexpectedly, and the track itself is a serious 4WD route that should not be attempted without experience.

The Blowhole suits experienced, self-reliant shore divers who are fit enough for the walk and able to read conditions. It is a destination for a special calm day, perhaps combined with camping in the park. Carry out everything you carry in and respect park rules.

Let someone know your plans before heading down, as help is a long way off.

Deep Creek Conservation Park is about 1 hour 40 minutes (80-100 km) south of Adelaide via Main South Road and Range Road near Delamere. A park entry fee applies (about $12.50 per vehicle per day). From the dirt-road car park, a short but steep and rocky 4WD-only track descends to Blowhole Beach and requires low-range gearing and experience; otherwise walk down, which involves several hundred metres of steep track – hard work with dive gear.

Enter from the beach anywhere along the shore.

Blowhole Beach faces south-west onto Backstairs Passage and the open Southern Ocean approaches, so it takes the full force of south-westerly swell and wind. Sources warn of heavy current and freak waves. Dive only on rare flat days after a period of northerly or north-easterly winds and small swell, ideally at slack tide.

Summer and early autumn give the best chances. Visibility is often excellent because of clean oceanic water.

With a local guide, enter from the beach at a sheltered spot, explore the reef close inshore at 4-8 m and stay near the exit. Turn early and do not venture into the current.

No operator; SDFSA strongly advises diving with someone who knows the area on the first visit.