Meet the site
Three Sisters is widely regarded as one of the best dives on the Cairns outer reef; Passions of Paradise calls it one of the truly great dives on the Great Barrier Reef. Three large bommies rise from a sandy floor at depths of roughly 12 to more than 30 m, the second and third sisters reaching to within a metre of the surface. The gap between those two is only about 3 m wide and is known as Gorgonian Gorge for the sea fans that line it; bigger fish use it as a corridor, and swimming through it is the highlight of most dives here. Each sister has a slightly different character. Great Barrier Reef Tours describes the second as a good place to explore the base at about 19 m, with blue-spotted lagoon rays and sharks on the sand, and the third as home to schools of fusiliers and snapper with brilliant yellow gorgonians along its wall. The bommies are pocked with swim-throughs, overhangs and crevices, and support schools of snapper, surgeonfish and sweetlips on their flanks. Sleeping whitetip reef sharks, turtles, moray eels, garden eels on the sand and cruising barracuda complete the picture, and the coral cover is healthy and varied. The depth range lets divers of all levels enjoy it: new divers can stay on the upper faces, while experienced divers can drop to the base of the outer bommie. Snorkellers can see the tops of the second and third sisters in clear water. It is also a strong night dive in calm weather. Note that Michaelmas Reef has an unrelated site of the same name.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Three Sisters (Milln Reef) is recorded as Pinnacle/Bommie in Cairns. The listed access is boat (day trip). Confirm the actual meeting point, route and permission to visit; a map pin does not establish any of these.
Topics flagged by the stored research
These are questions prompted by the existing notes, not a verified or complete hazard assessment.
- Current and timing
- Ask how the operator assesses the current window for the actual route. Historical tide notes are not a departure instruction.
- Other water users
- Ask about vessel activity, exclusion areas and the agreed surface arrangements.
- Planned depth
- Confirm the intended route and training requirements; the recorded maximum is not a target.
- Water movement
- Ask how swell and local exposure affect the proposed entry, exit and route.
Historical access notes exist for this record, but have not been independently verified for current use. Request current directions from the operator or site manager rather than following an old entry description.
Questions, answered
Is Three Sisters (Milln Reef) suitable for my certification?
The record lists Advanced Open Water. That does not establish suitability for every route or day. Share your training, recent experience and equipment needs with the operator and ask about the specific proposed dive.
Can I book Three Sisters (Milln Reef) through YouDive?
YouDive is an independent research directory. Contact an operator directly to confirm whether it currently runs the trip, the inclusions and the booking terms.
What you might see
Whitetip reef sharks, green turtles, barracuda, snapper, sweetlips, surgeonfish, fusiliers, moray eels, garden eels, blue-spotted lagoon rays, yellow gorgonian fans
Location
Group of three large bommies on Milln Reef, about 55 km east of Cairns, with the narrow Gorgonian Gorge between the second and third sisters.
Facilities nearby
Departs Reef Fleet Terminal / Marlin Marina, Cairns: toilets, cafes, paid parking; dive gear, tanks and lunch supplied on board
Before you make plans
Conditions, access and operator schedules can change. This is a location guide, not a dive plan. Ask a local operator about current conditions and suitability for your training and experience.
Sources & further reading
tropicalnorthqueensland.org.aupassions.com.augreatbarrierreeftours.comcairnsdiveadventures.com.audive-the-world.comRecord updated 27 Sept 2026. Source claims are being reviewed.