The North Mole Barge is one of Perth's most popular shore wrecks. It is widely called the Gareenup Wreck, but its identity has never been confirmed. It is an iron-framed steel hopper barge with steam machinery, probably used for dredging in the Swan River and Fremantle Harbour. It originally sank about 200 m from its present site and was raised and relocated in 1988 during port works, coming to rest upright 180 m north of the North Mole in 8 m.

The hull is about 20 m long. Its iron skeleton of ribs, frames and plating is open in places, and divers can swim through the roughly 10 m between entry and exit openings. Some sections have been crushed, reportedly by a lost houseboat. About 30 m away lie more pieces of wreckage, including coiled pipe and the ribs of another vessel, probably from the area's ship-breaking history. Seagrass meadows surround the site.

Life is varied for such a small site. Aggressive scalyfin defend the hull, bight and sparsely spotted stingarees rest on the sand, fingered dragonets are a local speciality, and baldchin groper, wrasse and schools of small fish use the structure. Sponges and ascidians cover the steel.

The difficulty is getting in and out. The ramp at the disabled fishing platform is steep, slippery and exposed to waves, and falls here have caused serious injury. The pole trail laid by local divers has solved the problem of finding the wreck. With a rope, calm conditions and patience it is a rewarding dive for Open Water divers with some shore experience.

Drive out along North Mole Drive from Port Beach Road, North Fremantle, and park near the disabled-access fishing platform (do not use permit bays without a permit). Enter down the ramp beside the platform: sit on the rocks, wait for a wave to lift you and slide in; a giant stride is dangerous because of submerged rocks. The wreck lies about 180 m from the mole on a bearing of 355°, a 5–8 minute swim.

Local divers have installed a trail of stainless-steel poles from the base of the ramp to the wreck. Bring 10–15 m of rope to tie off at the ramp; it makes the exit far easier.

The mole shelters the barge from south-westerly swell, which makes it the main sheltered option north of the river when southerly systems close other sites; it has been dived in 1.8 m swell with a 12-second period. The entry and exit are the limit: swell over about 1.5 m, or northerly and north-westerly winds, make the ramp dangerous. Dive in the morning before the summer sea breeze.

Swan River outflow on the ebb tide lowers visibility, especially after winter rain.

Descend at the base of the ramp and follow the pole trail on 355° for about 180 m to the barge in 8 m. Circle the hull, look inside the open compartments from the entry points without going deep, then check the scattered wreckage and coiled pipe about 30 m away. Return along the pole trail and surface at the ramp, using the rope to exit.

Mostly dived independently; Perth dive clubs and some shops run occasional guided shore dives. Howies Scuba publishes detailed entry notes.