Trap Reef is a pinnacle and reef system just outside Bicheno's harbour, north of Governor Island. Its top sits at about 13 m and it is cut by kelp-covered gutters that deepen from 17 m to 21 m and reach the sand at around 29 m, with the deepest parts of the site close to 35 m. Scuba Chronicles notes that surf breaks over the reef in any swell, reaching several metres, which gives the site its name.

Michael McFadyen's dive in the north gutter found a reef covered in kelp, as with most Tasmanian sites, with scattered sponges and small gorgonians on the walls. The Combined Clubs guide adds finger sponges, ascidians and bryozoans. Fish life is good: bastard trumpeter, yellowtail, seapike, wrasse, leatherjackets, banded morwong, old wives and long-snouted boarfish, plus resident magpie perch and butterfly perch. Yellow sea spiders and yellow nudibranchs are common on the kelp.

The site is structured around its gutters, which make navigation simple and give a pleasant sense of swimming along narrow canyons with walls of kelp. There are also swim-throughs and overhangs along the sea floor. It is less colourful than the deep Governor Island sites but has more fish, and it is often chosen when the Governor Island walls are affected by surge.

Trap Reef suits Advanced Open Water divers and is a good second or third dive. Visibility can be lower than on the eastern side of the island, as McFadyen found on a flat-calm February day with 10 m visibility.

Bicheno is on the Tasman Highway (A3), about 2 hr 15 min (180 km) from Hobart and 2 hr (160 km) from Launceston. Boats launch from the small ramp at The Gulch (Waubs Gulch), the narrow channel between Governor Island and the town foreshore off Esplanade; there is trailer parking beside the ramp and fishing co-op. The Governor Island sites are only 2-5 minutes' run out of the Gulch.

Tasmanian boat diving is almost always done as a live-boat drop and pick-up rather than at anchor. Trap Reef is just outside the harbour, a 2-3 minute run from the ramp. McFadyen dived the north gutter as a live drop and pick-up without anchoring; surf breaks over the reef in any swell, so the skipper chooses the drop point carefully.

The Governor Island sites face east into the Tasman Sea, so easterly and north-easterly swell over about 1.5 m, or a fresh easterly/north-easterly sea breeze, makes them rough and surgy and can close the Gulch entrance. Westerly and north-westerly winds blow offshore and give the flattest seas; southerly swell wraps in and stirs the bottom, and a big southerly can drop visibility under 2 m for days. Winter (June-September) usually brings the clearest water (20-30 m) and most settled westerly weather; summer afternoons are often spoiled by the NE sea breeze, so dive mornings.

Trap Reef breaks heavily - surf of several metres - in easterly or large southerly swell, so it is a calm-day site only.

Drop to the reef top at about 13 m, descend into the southern-most gutter (17 m deepening to 21 m) and follow it west to the sand edge at about 29 m. Turn south and then east along the southern side of the reef, rising back to the reef top for a safety stop in the kelp.

No confirmed full-time commercial dive operator in Bicheno as of 2026: the long-running Bicheno Dive Centre was reported closed (Michael McFadyen) although some tourism pages still list it - verify before travelling. Sites are dived by club boats (Tas Uni Dive Club, Tasmanian Scuba Diving Club, Leven Scuba Club), the annual Combined Clubs Weekend each June, and occasional trips from Launceston (Tasmanian Divers) and Hobart (Go Dive Tasmania) shops.