The Gold Coast Seaway is the channel that connects the Broadwater to the ocean at the northern end of The Spit, and its southern breakwater – with the sand bypass pipe running along the seabed beside it – is one of the busiest and most rewarding shore dives in Australia. Gold Coast Dive Adventures calls it the best dive site of any Australian city, and local guides list more than 400 species recorded. The South Wall is a rock breakwater about 700 m long with purpose-built access stairs and rails, so entries are easy despite the rocks.

Close to the stairs, the rocks slope down to 5-7 m – a good area for snorkellers and beginners. About 50 m to the right lies the sand bypass pipe, which carries sand pumped from the beaches to the south under the entrance to keep the channel open. It was originally buried about 6 m under the sand but now stands proud of the bottom, running out to around 14-16 m, and it has become an artificial reef.

A second pipe, the short pipe, carries treated sewage and lies to the left. The marine life is remarkable for a city site: giant Queensland groupers, jewfish (mulloway), sweetlips, eagle rays, cownose rays, bull rays, shovelnose rays, bigeye trevally schools, wobbegongs and occasional whaler sharks, with turtles, moray eels, lionfish, stonefish and scorpionfish among the rocks. It is also a first-class macro site: nudibranchs, seahorses, frogfish, shrimps and crabs are common, and at night octopus, eels, crayfish and slugs emerge.

Everything depends on the tide – it can only be dived safely around the high-tide slack – but for divers who time it right, the Seaway offers a quality of dive few cities can match.

From Surfers Paradise drive north along Main Beach Parade and Seaworld Drive to the end of The Spit (about 10 minutes; roughly an hour from Brisbane). Park in the Doug Jennings Park car park facing South Stradbroke Island (the front car park closes at 8 pm – use other parking for night dives). Walk about 50 m to the access stairs with rails over the rocks; there are three main access points.

The sand bypass pipe lies about 50 m to the right of the main stairs, and the short pipe is just to the left. Enter down the stairs, descend along the wall and follow the pipe; exit by the same stairs.

Tidal site – dive only towards the end of the incoming tide and through the high-tide slack. Enter about 30-60 minutes before high tide and plan to be out within about an hour of the turn; the slack window is short and the ebb runs very hard, bringing turbid Broadwater water and treated sewage vented from the second pipe after high tide. Avoid the outgoing tide entirely.

Large easterly swells push surge into the entrance and reduce visibility. Visibility ranges from 3 to 15 m and is best on a big high tide in dry weather; heavy rain ruins it for days.

Enter by the main stairs about 30-60 minutes before high tide. Descend the wall and swim right about 50 m to the sand bypass pipe, follow it out to 14-16 m, then work back along the rocks of the wall at 5-8 m. Turn when you reach half gas (turn at about 120 bar from 200 to surface with 50 bar), do the safety stop against the wall and exit by the stairs before the tide turns.

Night dives possible when high tide falls after dark.

Gold Coast Dive Adventures (Runaway Bay) – guided shore dives and night dives; Queensland Scuba Diving Company (Main Beach), Rick's Dive School (Hope Island), Southport Fishing & Dive Centre (tank hire, 10 minutes away) and other Gold Coast shops run regular guided Seaway dives.