Largs Bay Jetty is a heritage-listed jetty on the Esplanade at Largs Bay, just north of Semaphore and opposite the landmark Largs Pier Hotel, which was once used as a navigation reference by sailors. Fishing guides describe it as shorter and shallower than Semaphore Jetty, set over the same sandy coast. It is on this region's list but does not appear in any published dive guide, so this is a factual profile rather than a dive guide.

Expect a very shallow, sandy dive among the piles with some growth, small fish and crabs, and possibly cuttlefish and octopus at night. The broader Largs Bay area sits south of Outer Harbor and the entrance to the Port River, and the Adelaide Dolphin Sanctuary covers the nearby Port River and Barker Inlet, so dolphins are regularly seen along this coast. The practical appeal is limited to local residents wanting a calm-day snorkel or exploratory night dive close to home.

Visibility is often poor, and on hot days the beach and jetty are busy. For better diving nearby, the Outer Harbor breakwater and wharf offer a sheltered bad-weather option, and the Norma wreck lies about 5 km offshore for divers with a boat. Divers should keep well clear of anglers, be visible to swimmers, and treat this as a shallow snorkel rather than a scuba destination.

Reports on what lives here would help fill a gap in the local record. The Largs Pier Hotel and Esplanade kiosks are right behind the jetty, which makes it an easy spot for a quick evening snorkel in summer.

Largs Bay is about 25 minutes north-west of the Adelaide CBD. Park on the Esplanade near the heritage Largs Pier Hotel. Enter from the beach beside the jetty and snorkel out along the piles; there are no documented diver stairs.

Gear up at the car and walk across the sand; the carry is short. Swim out on the surface with a torch and surface marker buoy, and stay beside or under the jetty rather than out in the swimming area. Entry and exit through small shore-break waves is easiest at mid to high tide.

These northern metro jetties sit on a shallow, sandy, west-facing coast. They are only worth diving in flat conditions after several days of easterly (offshore) winds; any westerly or south-westerly wind or swell stirs up the sand and turns the water milky, and the summer sea breeze usually arrives by early afternoon. The tidal range is small, but low tide leaves little water under the inshore half.

Visibility falls sharply after rain because of stormwater and river outflow along the coast. Night dives on calm evenings give the best chance of cephalopods.

Enter from the beach beside the jetty, snorkel out to the deeper outer half, then descend and work slowly along the piles with a torch, keeping well clear of fishing lines. Return along the other side and exit on the beach.

No dive operator uses this jetty; nearest shops for fills and advice are in Glenelg (Adelaide Scuba, The Dive Shack) and Edwardstown (Underwater Sports).