Hobart's wharves at Sullivans Cove have been the heart of the port since the colony's earliest days, and the muddy seabed beneath them is littered with two centuries of dropped and discarded objects. The Marine Life Network guide describes depths of 6-12 m, a muddy bottom 'well flushed by the ocean tides', and marine life including school fish, sea stars and seahorses, along with the invasive Northern Pacific seastar (Asterias amurensis), which arrived in ballast water and is now abundant in the Derwent. The attraction for most who dive here is historical: bottles, ceramics and other artefacts from the port's long history lie in the mud, although these are protected and should not be removed.

The wharf pylons are encrusted with invertebrates and provide shelter for fish and seahorses. The practical obstacles are considerable. TasPorts permission is required; the port is busy with fishing boats, ferries, cruise ships and Antarctic vessels; and entry and exit are by wharf ladders, best at high tide with assistance.

Visibility is usually very low. For these reasons the wharves are dived rarely and only by authorised groups. It is included here for completeness and history rather than as a recommended recreational dive; those interested should approach local clubs, which occasionally organise authorised dives, and contact TasPorts well in advance.

The Maritime Museum of Tasmania, a short walk away, holds many objects recovered from Hobart's waters. Anyone who does obtain permission should plan the dive around the tide and vessel schedule, use a surface marker and attendant, and treat every object on the bottom as protected heritage material.

The wharves are in the Hobart CBD at Sullivans Cove, with paid city parking nearby. The Marine Life Network guide stresses that diving requires permission from TasPorts, the port authority, and that entry is best at high water, with assistance needed to exit via ladders. Do not attempt without written permission and a surface support person; vessel movements, including Antarctic and cruise ships, ferries and fishing boats, make unauthorised diving dangerous and illegal.

The Derwent estuary is sheltered from ocean swell, but strong northerly or southerly winds blow along its length and raise a short, steep chop; the Marine Life Network notes the region can become very rough in gales, even in the river. Visibility is the limiting factor: it is usually low (1-5 m) and worst after rain, when the Derwent's tannin-stained, silty floodwater spreads through the estuary. Dive after a dry spell, on a high or flood tide that brings in clearer marine water.

There is a noticeable but generally mild tidal flow. Diving is possible year-round; winter water is cold (9-11 °C). The Marine Life Network notes the wharves are well flushed by ocean tides; choose high water for entry and exit.

With permission and a surface attendant, enter at high water from the ladder, descend to the mud at 8-12 m and search slowly along the wharf pylons for artefacts and seahorses. Exit on the same ladder with help.

Authorised dives only; surface support and dive flag required; coordinate with TasPorts on vessel movements.

No commercial operator; occasional authorised club, research or commercial diving only.