Courts Island is a remote island off the southern coast of Bruny Island. The Marine Life Network guide gives it one of its highest ratings, describing its western side, sheltered from south-easterly weather, where cliffs drop away sharply to a series of reefs broken by long sandy gullies in 20-25 m. It notes colourful sponges and small marine life on the rock faces, good visibility, and that the site is beautiful but difficult to reach.

The combination of steep cliffs, deep reef and clean water from the Southern Ocean produces rich invertebrate growth: sponges in many colours, sea whips, jewel anemones and hydroids cover the rock, while butterfly perch, wrasse, morwong and leatherjackets move along the reefs. The sandy gullies give the dive structure, channelling divers along the reef lines. Fur seals from the Friars colony may pass by.

Because it is so remote, Courts Island sees very few divers and is essentially an expedition site for self-sufficient boat crews. Plan it as part of a south Bruny trip combining Quiet Bay or Partridge Island, with plenty of fuel and a sheltered fallback. Mobile coverage is patchy; carry a VHF radio, EPIRB and oxygen.

For experienced divers who can get there on a calm day, it is one of the finest reef dives in the D'Entrecasteaux–Bruny region. The rarity of visits also means the reef is largely undisturbed, and marine life is correspondingly relaxed. Photographers should bring wide-angle gear for the cliffs and gullies, as visibility here is often among the best in the region.

Bruny Island is reached by the vehicle ferry from Kettering (about 35 km, 40 minutes south of Hobart via the Southern Outlet and Channel Highway) to Roberts Point on North Bruny; the crossing takes about 20 minutes and runs frequently, but book or queue early in summer. Courts Island lies off South Bruny's southern coast and is reached only by boat in very calm weather – from Adventure Bay around Tasman Head, from South Bruny launching points near Cloudy Bay, or from Dover across the southern channel. Expect a run of 45-60 minutes.

Anchor on the western side, which is sheltered from south-easterlies.

Courts Island is fully exposed to the Southern Ocean. The Marine Life Network notes it requires very calm weather, with the western side sheltered from south-easterly weather. Southerly and south-westerly swell, present most days, closes the site; aim for a high-pressure system with light northerly winds in late summer or autumn.

Visibility is usually good on the rare days it can be reached. A south-westerly change makes the long return dangerous; monitor forecasts and leave early.

Descend on the western cliffs, drop to 20-25 m along the reefs and sandy gullies, and explore the sponge-covered rock faces before ascending along the cliff.

No regular operator; private expedition boats only.