Port Germein's jetty is famous as one of the longest timber jetties in Australia – about 1.5 km today – built in 1881 to reach deep enough water across the vast tidal flats of upper Spencer Gulf for sailing ships loading wheat. It is a heritage structure and a popular walk and fishing spot rather than a recognised dive site. Even at the end, the water is shallow: roughly 3-4 m at high tide, over sand and seagrass.

The piles support algae and modest encrusting growth, with crabs, shrimps and small fish. Blue swimmer crabs are abundant in summer, and schools of tommy ruff, garfish and yellowfin whiting move through, with squid at night. Dolphins are seen in the gulf.

The dive is essentially a novelty – the chance to say you have dived the end of one of the country's longest wooden jetties – and requires a long walk with gear and careful timing for high tide. Visibility in upper Spencer Gulf is generally limited. It suits divers passing through the Southern Flinders/upper gulf area with an interest in heritage jetties.

For quality diving in the upper gulf, head across to Whyalla and the cuttlefish coast. Allow at least 20 minutes each way for the walk along the jetty, and carry plenty of water in summer, when temperatures on the exposed boardwalk can be extreme. The town's historic pub and caravan park make it a pleasant overnight stop.

From Adelaide drive about 240 km (2 hours 45 minutes) north via Port Wakefield and Port Pirie on the Augusta Highway, turning west to Port Germein (20 km north of Port Pirie). The jetty starts at the foreshore in town; it is roughly 1.5 km long, so carrying dive gear to the end is a long walk (consider a trolley). Enter from the end at high tide – the flats beneath much of the jetty dry out at low water.

Port Germein faces west across upper Spencer Gulf. Westerly and south-westerly winds raise chop on the shallow flats and cloud the water; easterlies blow offshore and give the calmest conditions. Tides are large in the upper gulf and the flats drain extensively, so only dive at high water.

Summer water is warm (mid-20s); winter is cold.

At high tide, enter at the end, circle the outer piles in 3-4 m looking for crabs and small fish, and exit before the tide falls.

No operator; a novelty dive done occasionally by visiting divers.