The Marine Life Network guide rates it 6 out of 10 and says it is often used for dive courses: a long swim over shallow short brown algae (about 5 m maximum) followed by abundant fish life around a rock that is visible at low tide and covered by 1-2 m at high tide. The Leven Scuba Club lists Popeyes Rock among the Rocky Cape mix of shore and boat dives.

In the shallows there are a few abalone, wrasse, magpie perch, zebrafish, sponges and ascidians. Around the rock the fish list grows: long-snouted boarfish, barber perch, leatherjackets, red mullet, zebrafish, senator wrasse and globefish, with pipehorses, cuttlefish, cowfish and nudibranchs, and bullseyes in the crevices. The crevices are packed with sponges, ascidians, cup corals, hydroids and bryozoans. At night bullseyes school on the bottom and octopus and other nocturnal hunters appear. 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.

Rocky Cape National Park is off the Bass Highway between Wynyard and Stanley, about 30 minutes west of Wynyard and 1 hr 15 min west of Devonport (Spirit of Tasmania terminal). A Parks Pass is required. Boats launch at the Rocky Cape boat ramps (the western ramp at Mary Ann Bay suits boats up to about 5 m), Sisters Beach or Boat Harbour; ramps are shallow and weedy at low tide, so a 4WD tow vehicle helps.

Drive through the park to the turning area north of the toilet block on the eastern side of the cape. Enter from the shore and make a long swim over shallow weed beds (about 5 m maximum) to Popeye's Rock, which shows at low tide and is covered by 1-2 m at high tide.

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.

The eastern side is sheltered from westerly weather and is often used for courses; it is exposed to easterly winds.

Swim out over the brown algae to Popeye's Rock, then circle it slowly at 5-10 m, searching crevices for macro life; return the same way. Excellent at night, when bullseyes school on the bottom. 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.