Meet the site
Horseshoe Reef is the northern edge of Agincourt Reef No. 2 run as a drift dive, and it is one of the more exhilarating dives on the Port Douglas day-boat roster. The Silverseries and Poseidon site notes single out one image: huge schools of luminescent blue fusiliers hugging the reef wall. On a good tide you fly past a continuous curtain of them. The reef edge drops from about 5 m down to around 20 m, with a mix of hard coral buttresses, overhangs and soft coral growth. The current funnelling along the edge carries plankton, which is why the fusiliers are there in such numbers, and why the predators follow. Trevally and Spanish mackerel make fast passes through the schools, red bass and humphead Maori wrasse patrol the wall, and big humphead parrotfish move along the reef top in herds. Keep watching the blue side as well as the wall: reef sharks and eagle rays are regular sightings on this kind of edge. As a drift, the dive involves very little finning – you position yourself a few metres off the wall, match depth with your buddy and let the water do the work. The guide carries a surface marker buoy and the boat's tender tracks the group and collects everyone at the end. The main skills required are good buoyancy control and staying close to the group, which is why it is best for divers with a few dives under their belt. On slack or neap tides the site can instead be dived from the mooring as an out-and-back along the wall. Visibility commonly runs 20 m or more. Horseshoe Reef suits confident open water divers and anyone who enjoys the sensation of drift diving. It offers a big-fish, big-school experience that contrasts nicely with the gentler coral gardens elsewhere on Agincourt 2.
What you might see
Blue fusiliers (luminous), giant and bluefin trevally, Spanish mackerel, red bass, humphead Maori wrasse, bumphead parrotfish, reef sharks, eagle rays
Location
A drift dive along the northern edge of Agincourt Reef No. 2, where the reef wall is lined with schooling blue fusiliers.
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
silverseries.com.auposeidon-cruises.com.auRecord updated 27 Sept 2026. Source claims are being reviewed.