The Glory Hole, also called Sisters Cave, is rated 5.5 out of 10 by the Marine Life Network guide, and the Leven Scuba Club notes it is the only shore dive at Sisters Beach. Red quartzite headland rocks form caves and swim-throughs; a boulder maze has crevices and swim-throughs, a large cave on the seaward side holds bullseyes, and gardens of Macrocystis and crayweed grow around it in 5-10 m. Yellow zoanthids, lace bryozoans, cup corals and sponges cover the rock faces; small zebrafish and wrasse are common, fish life improves with depth, and large stingrays are seen. Small abalone are present but few crayfish. Local divers typically combine two or three Rocky Cape and Sisters Island sites in a day, choosing the side of the cape that suits the wind and the state of the tide.

The Rocky Cape and Sisters Island area is, in the Leven Scuba Club's words, the best collection of dive sites on the north-west coast. The quartzite of Rocky Cape - some of the oldest rock in Tasmania - forms gutters, ledges, caves and bommies, and the tidal flow along Bass Strait keeps sponges, gorgonians, sea pens and bryozoans well fed. Michael McFadyen, diving here in February 2008, recorded 18-19 °C water and 20-25 m visibility, figures that surprise divers used to the east coast.

Rocky Cape National Park also protects Aboriginal cave sites and coastal heath above the water, and a Parks Pass is required for vehicles. The nearest hyperbaric chamber is the Royal Hobart Hospital, about four hours' drive away, so conservative profiles and oxygen on the boat are essential.

Sisters Beach is a small village in Rocky Cape National Park, off the Bass Highway about 25 minutes west of Wynyard (1 hr 15 min from Devonport). The Sisters Beach boat ramp is the launch point for Sisters Island (about 3-5 km); Boat Harbour ramp further east is an alternative. Ramps are shallow at low tide.

From Sisters Beach township follow the gravel road along the southern edge of the beach to the turning circle and pebbly beach. Enter and make a long swim over the shallow tidal flat to the headland; high tide is preferred, as the quartzite is very hard to exit at low water.

The north-west coast faces Bass Strait: north-westerly to north-easterly winds and westerly swell make it rough, while southerly winds blow offshore and give flat seas - light airs and sunny days are relatively common from January to April. Easterly gales are common in the warmer months and close the eastern faces of Rocky Cape and Sisters Island. Tidal streams run along the coast (eastward on the flood), and several boat sites are only comfortable around slack water.

High tide preferred; a noticeable current runs in the gap between shore and rock.

Swim to the headland, explore the boulder maze and swim-throughs, visit the large seaward cave full of bullseyes, and return through the Macrocystis and crayweed before the tide drops. Turn at a third of gas to allow for the swim back and a possibly harder exit, finish with a 3-minute safety stop at about 5 m if the depth allows, and exit where you entered unless an alternative exit has been checked beforehand.

No confirmed commercial dive operator on the north-west coast as of 2026 (older guides mention dive services in Wynyard and Devonport - verify). Sites are dived mainly by the Leven Scuba Club (Ulverstone), other north-west club members and visiting divers with their own boats; Tasmanian Divers (Launceston) runs occasional northern trips.