Meet the site
Phil's Lagoon is an unusual formation on the southern side of Third Sister reef off Tongue Reef, visited by Wavelength Reef Cruises. The operator describes a virtually enclosed lagoon full of coral and reef fish, with an exterior drop-off where grey reef sharks pass and schools of plankton-feeding fusiliers gather. The enclosed lagoon is the main attraction. Protected from waves, it supports delicate coral growth and a dense community of reef fish. Enormous giant clams are a feature, and turtles are frequently seen. The calm water makes it ideal for snorkellers of all abilities. Outside the lagoon, the reef drops away, providing a contrast. Grey reef sharks cruise along the drop-off, and schools of fusiliers feed on plankton in the water column. Snorkellers can look over the edge into deeper water, and divers on a charter would find a wall to explore. No depth figures are published; the lagoon is shallow, and the drop-off extends into deeper water. The site should not be confused with Phil's Reef or Phil's Backside on the Agincourt complex. The lagoon is sheltered enough to be used on days when the more exposed corner sites are too lively. Wavelength is a snorkel-only operator whose marine biologists guide in-water tours and give reef talks; its skipper chooses three sites each day from the company's exclusive moorings according to wind and tide, so a particular site is never guaranteed. Scuba divers wanting to dive the Sister reefs need a private charter, and because the site names are Wavelength's own, other operators may not recognise them.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Phil's Lagoon (Tongue Reef Sister reefs) is recorded as Reef in Port Douglas. 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.
- Other water users
- Ask about vessel activity, exclusion areas and the agreed surface arrangements.
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 Phil's Lagoon (Tongue Reef Sister reefs) suitable for my certification?
The record lists Snorkel/Any. 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 Phil's Lagoon (Tongue Reef Sister reefs) 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
Giant clams (enormous), green turtles, grey reef sharks, fusiliers, reef fish, hard corals
Location
A virtually enclosed coral lagoon on the southern side of Third Sister reef off Tongue Reef, with a drop-off outside.
Facilities nearby
Departs Crystalbrook Superyacht Marina, Wharf Street, Port Douglas – car parking, toilets, cafes and restaurants at the marina; dive shops in town for gear hire and air
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
wavelength.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.