Bunker Bay is a remote bay on Maria Island's eastern side that the Marine Life Network guide rates 6 out of 10 as a second-tank location, sheltered from the prevailing easterly weather. Depths are 10-20 m.

Bull kelp and cray weed cover the reef, with bullseyes, rock cod, banded morwong, wrasse, rosy wrasse and butterfly perch among the fish, and crayfish and abalone in the cracks. The guide stresses that this is a remote, exposed area where an experienced boat operator is essential.

Bunker Bay suits experienced divers on a self-sufficient trip down the eastern side, usually as a shallower dive after Mistaken Cape. There are no facilities on this side of the island, and no landing points close to the bay.

Maria Island is a national park with no permanent residents apart from rangers, and the Darlington settlement preserves convict-era buildings from 1825 onwards. The marine reserve along the island's northern and western shores has been no-take since 1991 and has been used for long-term studies of how protection affects rock lobster and fish numbers, so reef life inside it is noticeably richer than outside.

Maria Island's boat sites are rarely visited because there is no operator on the island and the eastern coast is a long way from the Triabunna ramp. Visitors with their own boats should carry oxygen and a radio, check the forecast for Mercury Passage as well as the open coast, and remember that the Royal Hobart Hospital chamber is roughly two hours away by road once back at Triabunna.

Triabunna, on the Tasman Highway 1 hr 15 min (85 km) north-east of Hobart, is the gateway. The Maria Island passenger ferry (Encounter Maria Island) runs several times daily from Triabunna to the Darlington jetty, about 16 km and roughly 30-45 minutes; it carries people and small amounts of luggage but not vehicles, and dive cylinders should be cleared with the operator first. Private boats launch at the Triabunna ramp (best), Saltworks Road ramp, or Orford (shallow bar at the Prosser River mouth - difficult at low tide).

Bunker Bay is on the remote eastern side of the island; the Marine Life Network guide stresses that an experienced boat operator is essential. Allow over an hour each way from Triabunna.

Maria Island's western and northern shores (Darlington, Fossil Cliffs, Painted Cliffs) are sheltered from easterly ocean swell but exposed to strong westerlies and north-westerlies blowing across Mercury Passage, which are common in winter and spring. The eastern side (Mistaken Cape, Bunker Bay) faces the open Tasman Sea and needs westerly weather and small swell. Southerly swell wraps around Cape Peron and the southern end.

Visibility drops after rain as runoff flows from the Prosser River into Mercury Passage. Bunker Bay is described as sheltered from prevailing easterly weather, so it is the second-dive option on the eastern coast.

Anchor or drop in the bay at 10-12 m and follow the reef out to 15-20 m through the bull kelp and cray weed, then return shallower. Turn the dive at half gas (thirds where current or overhead sections are involved), deploy an SMB before surfacing for the live-boat pick-up, and complete a 3-minute safety stop at about 5 m where depth allows.

No operator based on Maria Island. Hobart shops run occasional trips: Go Dive Tasmania has offered Ile des Phoques seal dives and filmed Troy D dives; Tasmanian Scuba Diving Club and Tas Uni Dive Club run club trips from Triabunna. Most diving is from private boats.