The Monument is a rocky spire off the Tasman Peninsula, south of the Lanterns – the chain of islets and stacks that extends from Cape Hauy, home of the famous Totem Pole and Candlestick climbing stacks. The Marine Life Network guide records the Monument at 15-30 m, with a wall drop-off, strong current and butterfly perch among the marine life. Its position beyond the shelter of Cape Hauy means clean oceanic water and excellent visibility on good days, and the current that sweeps past feeds a dense covering of sponges and other filter feeders on the wall.

Butterfly perch school in the current off the spire, with banded morwong, wrasse and the odd real bastard trumpeter, and fur seals from colonies along this coast may join divers. The dive is a short, energetic one for experienced divers: current dictates the plan, and the spire provides only a small area of shelter. It is not a regular charter site, but it is one of a cluster of dramatic locations around Cape Hauy that private boats from Fortescue Bay can reach quickly on calm days.

Combine it with the more sheltered Monument Bay close by for a second dive. Documentation is limited to older guides; confirm details locally before diving. Cape Hauy is also on the route of the Three Capes coastal cruises and the Cape Hauy walking track, so expect boats and walkers watching from above on fine days.

Treat the Monument as a site for a well-found private boat with an experienced skipper who can follow divers' bubbles in current, and plan conservatively for the cold and the swim to the pick-up.

Boat access only. Launch at the Fortescue Bay boat ramp (Fortescue Road, 12 km gravel from the Arthur Highway near Taranna; park pass required) and run south-east around Cape Hauy, about 10-15 minutes. Charters from Pirates Bay, Eaglehawk Neck take about 30 minutes.

There are no moorings; use a live boat because current runs past the spire. The Fortescue Bay ramp has trailer parking beside the campground but no fuel or supplies; bring everything, including filled cylinders from Eaglehawk Neck or Hobart.

The Tasman Peninsula faces the full Southern Ocean and Tasman Sea. South-westerly to south-easterly groundswell and strong easterlies are what cancel trips: operators generally need westerly or north-westerly winds with swell under about 1.5-2 m for the open-coast sites. Prolonged southerly swell pushes surge deep into the caves and gutters and churns visibility; after a big blow allow two or three days to settle.

Late summer and autumn (February-May) bring the most settled windows and the clearest water; winter can be glassy between fronts but fronts arrive every few days. The Monument is fully exposed beyond Cape Hauy and is swept by current; dive only on neap tides in calm westerly weather.

Drop on the up-current side of the spire, descend to 25-30 m on the wall and let the current carry you around the rock. Ascend the spire's lee side and send up an SMB for live-boat pick-up.

No regular scheduled trips; occasional Eaglehawk Dive Centre or Go Dive Tasmania visits in exceptional conditions; private boats from Fortescue Bay.