Hog Bay is where Penneshaw began – named for the pigs released by the French expedition of Nicolas Baudin – and in 1803 Baudin's crew carved an inscription on a rock at the bay. The original Frenchmans Rock is now in Penneshaw's Gateway Information Centre, and a replica marks the spot. Tourism Kangaroo Island recommends the reef in front of it, at the eastern end of Hog Bay Beach, for intermediate snorkellers, with magpie perch and scalyfin among the colourful reef fish.

The reef is shallow limestone and rock covered in brown algae and small kelp, with sponges under ledges and sand patches between. Besides magpie perch and scalyfin, expect wrasse, leatherjackets, sweep, old wives and the occasional cuttlefish, with seadragons possible in the weed. It is a pleasant, easy dive or snorkel within walking distance of the ferry terminal, cafes and accommodation, and it combines naturally with the Penneshaw jetty.

Backstairs Passage brings clear water but also tidal streams, which strengthen away from the beach, so shore divers should stay close to the reef and dive in calm weather. Little penguins nest along the Penneshaw foreshore, so take care at dusk. There is no dedicated dive documentation, and depths are estimated from the setting. It suits snorkellers, families and Open Water divers wanting a short, easy reef dive on arrival or before the ferry home. Visiting the original carved rock in the Gateway Information Centre before or after the dive adds context. Children and snorkellers can stay in the shallows close to the beach while divers work the deeper reef edge.

Take the SeaLink ferry from Cape Jervis to Penneshaw (45 min). From the ferry terminal walk or drive a few hundred metres to Hog Bay Beach on the Penneshaw foreshore. Park near the beach, gear up and walk to the eastern end, then follow the reef out in front of Frenchmans Rock (the replica of the carved rock, whose original is in the Gateway Information Centre).

Easy access with town facilities close by.

The Dudley Peninsula sites lie on Backstairs Passage and Eastern Cove, sheltered from the prevailing south-westerly swell but swept by strong tidal streams through the passage. Dive around slack water, particularly near headlands and islands; wind against tide creates steep chop. Easterly and north-easterly winds make Penneshaw and Hog Bay choppy, while south-easterlies affect Antechamber Bay and Cape Willoughby.

Summer and autumn bring the calmest days; winter westerlies are usually fine on this side of the island.

Enter at the eastern end of the beach, follow the reef out in front of Frenchmans Rock in 2-5 m, and return along the reef edge to the beach.

No regular operator – independent.