Blackmans Bay is a suburban beach just south of Kingston that offers two quite different shore dives at either end of the sand. Go Dive Tasmania lists Blackmans Bay North and South at 3-10 m for all certified divers, describing sheltered reefs with fish, sponges and rays. At the north end, near the blowhole reserve, the reef extends from the rocks to 8-12 m.

Tasmanian Divers runs evening fun dives here and notes crayfish, octopus and reports of weedy seadragons, recommending a torch for looking into crevices. The south end, as PADI's site notes describe, has several entry points with toilets and parking close by, shallow water that allows long dives, and a rocky point beyond the beach leading to a giant kelp forest. Species recorded include potbellied (big-belly) seahorses, sleeping draughtboard sharks, stingarees, biscuit sea stars and numerous fish, making it a favourite with photographers.

The presence of giant kelp so close to Hobart is noteworthy given the collapse of Macrocystis forests along much of Tasmania's east coast; its extent varies from year to year. The bay is a good all-weather option when westerlies blow, and a very popular night dive, when draughtboard sharks, octopus and crayfish are active. Visibility is the main variable: after rain the Derwent's plume and local runoff reduce it markedly, while dry spells can bring 8-10 m.

Easy access, facilities and varied reef make Blackmans Bay one of the most used training and fun-dive sites in southern Tasmania. With a dive shop five minutes away in Kingston, it is also the easiest place near Hobart to fit in a quick after-work dive.

Blackmans Bay is about 20 km (25 minutes) south of Hobart via the Southern Outlet and Kingston. For the north end, park on Ocean Esplanade near the blowhole reserve – Tasmanian Divers meets at the hut near the blowhole – and enter from the rocks or the beach corner. For the south end, PADI's site notes describe several shore entry points at the south end of the bay with public toilets and parking; a rocky point beyond the beach leads to a giant kelp forest, where the entry can be sharp and slippery.

Both ends are short walks from the car.

The Kingborough coast south of Hobart faces east across the lower Derwent and the northern D'Entrecasteaux Channel, so it is sheltered from the prevailing westerlies – the main reason Hobart divers use it year-round. Easterly and south-easterly winds put chop and small swell onto the shore and churn up the sandy bottom; strong southerly swell entering Storm Bay can also wrap in. Heavy rain is the biggest factor for visibility: the Derwent and local creeks carry tannin-stained, silty runoff that can drop visibility to 1-3 m for days.

Tidal flow is weak. Best after dry spells with westerlies, and in the calm mornings of late summer and autumn; night dives are popular year-round.

North end: enter near the blowhole, follow the reef out to 8-12 m and search the crevices with a torch for crayfish and octopus. South end: enter from the beach near the point, swim along the rocks to the kelp and explore it at 5-8 m. Return along a shallower contour.

Go Dive Tasmania – Blackmans Bay North and South listed as shore sites (3-10 m, all certified divers); Tasmanian Divers (Kingston) – evening fun dives from the north end; The Dive Shop Hobart and clubs – training and night dives.