Moonta Bay is the seaside end of the historic copper-mining town of Moonta, and its jetty is a quieter alternative to Port Hughes, three kilometres to the south. The Dive Shack notes its unusual L-shaped structure and describes it as a popular fishing spot where fish visits are sparse – garfish, tommy ruff and squid – and where divers must watch for fishing line. The jetty stands over sand and seagrass in shallow water, typically 3-5 m at the head.

The piles carry sponges, ascidians and algae, and patient divers find nudibranchs, crabs, small octopus and the occasional seahorse. Southern calamari are drawn to the jetty lights at night, and the seagrass fringes shelter juvenile whiting, garfish and pipefish. Blue swimmer crabs are common in summer.

It lacks the density of growth and critters that makes Port Hughes famous, and heavy fishing pressure means lines and hooks are a constant presence. Its advantages are its easy access, the family-friendly foreshore and the chance of a quiet dive when Port Hughes is busy. For most divers Moonta Bay is a secondary site – worth a dive if you are staying in town or want to add another Copper Coast jetty to your log, but not a priority.

Snorkellers enjoy the shallow inner section in summer. Its visibility depends, like all Copper Coast jetties, on the wind having some east in it. Night dives here are more rewarding than day dives: squid gather under the lights, and crabs and octopus emerge from the seagrass edge.

Combine it with Port Hughes for a relaxed two-jetty day on the Copper Coast.

From Adelaide drive about 165 km (2 hours) via Port Wakefield and Kadina to Moonta, then 2 km west to Moonta Bay. The jetty is on the foreshore at the end of the main road, beside the caravan park and swimming area. Park at the jetty head.

Enter by the jetty steps or walk in from the beach at high tide, and follow the jetty out and around its L-shaped head.

The Copper Coast jetties face west into Spencer Gulf, so easterly winds – anything 'with east in it' – blow offshore and give the flattest water and best visibility, often over 10 m. Westerly and south-westerly winds blow straight onshore, raise chop and stir the fine sediment, reducing visibility to a few metres. Ocean swell barely reaches this far up the gulf, so wind is the controlling factor.

Tides are moderate; shallow sections and entry steps are easier around mid to high water. Summer afternoons bring south-westerly sea breezes, so morning dives are more reliable. Heavy rain has little effect.

Fin out along the main arm, turn along the L-shaped head at 4-5 m and inspect the piles and seagrass edge, staying clear of anglers' lines, then return.

No operator; occasionally dived by locals and visitors as an alternative to nearby Port Hughes.