Blue Lagoon is the classic easy dive of the Rowley Shoals: a series of lagoons inside Clerke Reef with coral-rubble floors, sheer walls and coral heads in 8–12 m, reaching around 25 m in places. Divernet describes anemonefish, trevally schools and whitetip sharks; Diveplanit lists schools of barracuda, trevally, fusiliers, surgeonfish, snapper and sweetlips, with Maori wrasse, coral trout, mackerel, wahoo, rainbow runners, potato cod, moray eels, garden eels and dogtooth tuna; another Divernet feature recorded red, pink, yellow, white and orange soft corals, gorgonians and whip corals, with visibility beyond 40 m.

Because it is sheltered, it is often the first check-out dive of a trip and a favourite for snorkellers and night dives.

About the Rowley Shoals: three shelf-edge atolls — Mermaid, Clerke and Imperieuse reefs — rise from 300–700 m depths on the edge of the continental shelf about 260–300 km west of Broome. Mermaid Reef is protected in the Commonwealth Mermaid Reef Marine Park (a no-take national reserve); Clerke and Imperieuse form the State Rowley Shoals Marine Park, with sanctuary zones and limited recreational fishing areas. Clerke carries Bedwell Island and Imperieuse carries Cunningham Island and its lighthouse. More than 200 coral species and 700 fish species have been recorded, and only a few hundred divers visit each year in a season of a few weeks. The 2024–25 marine heatwave hit hard: AIMS surveys in April 2025 found very high (61–90%) coral mortality at Mermaid and Clerke across all habitats to 30 m, so hard coral cover is currently much reduced, although fish, sharks and the drama of the walls and drifts remain.

The Rowley Shoals lie about 260–300 km west of Broome and are reached only by liveaboard. Vessels depart Broome (e.g. Odyssey from its depot at 5 Lucas Street) in the evening and steam overnight (about 12–14 hours), spending 5–6 days diving the three atolls before steaming back; typical trips are 6–8 days.

Divers enter from the mothership or from tenders that drop and collect them on drift dives and inside the lagoons, where vessels anchor overnight.

The season is short — roughly September to December (most trips October–November) — when trade winds ease and seas calm between the dry-season easterlies and the cyclone season. Tides of around 4 m drive powerful currents through the atoll channels: drift sites such as Clerke Channel run fast on the flood, and walls and passages are timed by the crew. Inside the lagoons conditions are calm.

Visibility is 20–40 m, sometimes near 60 m, governed by the tide. Water 27–30 °C. Crossings can be rough if the wind is up.

Drop from the tender at a lagoon edge, follow the sheer walls at 8–15 m, then cross the coral-rubble floor between coral heads, looking for garden eels and anemonefish. Finish on a coral head for the safety stop.

Liveaboard only, from Broome: True North (luxury expedition ship), The Great Escape Charter Company (26 m catamaran), Odyssey Expeditions (M/V Odyssey, 24 m catamaran, max 20 guests, 8 days/7 nights, ~26 dives), Diversity Charters (MV Diversity III, 6-day cruises, max 12), plus Ocean Dream Charters and Kimberley Expeditions. Trips book out a year or more ahead.