Meet the site
Phil's Backside is a Scuba IQ favourite on the Agincourt complex, described by the operator as a site of deep bommies and a massive coral slope that is home to the biggest giant clams they have ever seen. Given how many clams Port Douglas guides see in a year, that is a strong recommendation. The dive is built around a broad slope of hard coral running down from the reef edge at about 5 m into deeper water, with isolated bommies standing off the bottom of the slope. The slope is densely covered – plate, staghorn and boulder corals interlock across it – and it holds a big population of reef fish: fusiliers and chromis above, parrotfish and surgeonfish grazing, and wrasse picking through the coral. The deeper bommies attract larger fish and are worth visiting early in the dive while you have plenty of gas and no-decompression time. The clams are the headline. Giant clams (Tridacna gigas) can exceed a metre across and live for decades; the ones here are huge, their mantles patterned in greens, blues and browns. Watch them close slowly as your shadow passes over, and resist the urge to touch – they are protected and sensitive to disturbance. Smaller Tridacna species with brighter mantles are scattered across the slope too. The name is a play on neighbouring Phil's Reef on Agincourt 3, and the site is on the same part of the complex; operators do not publish a precise depth range, so expect a slope running from the shallows to well beyond 20 m, with the dive normally planned in the 10–20 m band. It suits divers comfortable at moderate depth and anyone who enjoys long, relaxed swims over healthy hard coral. As one of the less frequently visited moorings, it tends to feel quiet even on busy days.
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 Backside (Agincourt Reef) 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.
- Planned depth
- Confirm the intended route and training requirements; the recorded maximum is not a target.
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 Backside (Agincourt Reef) suitable for my certification?
The record lists 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 Phil's Backside (Agincourt 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
Giant clams (Tridacna gigas and smaller Tridacna species), fusiliers, chromis, parrotfish, surgeonfish, wrasse, reef sharks, plate, staghorn and boulder corals
Location
A site on the Agincourt complex with deep bommies and a massive coral slope, known for exceptionally large giant clams.
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
scubaiq.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.