The Wreck Site on Agincourt Reef No. 3 combines two things: a sandy lagoon studded with imposing 12 m coral pinnacles, and the shallow remains of a fishing vessel. Silverseries describes the remains as those of a Taiwanese fishing vessel; the Visit Port Douglas Daintree dive guide calls it a roughly 70-year-old sunken fishing boat now heavily overgrown with coral, with swim-throughs, moray eels, cuttlefish, lionfish and barramundi cod. The wreckage is broken and low-lying rather than an intact hull, scattered across the shallows at around 5–8 m.

What remains – frames, plates and machinery – has been colonised by hard and soft corals so that it blends into the reef, and it provides hiding places that attract fish in numbers far out of proportion to its size. Moray eels poke from gaps in the plates, lionfish hover under overhangs, and cuttlefish are frequently seen hovering and changing colour nearby. The pinnacles are the other half of the dive.

Rising from sand at around 20–24 m, they are covered in corals and surrounded by red bass, spangled emperor, coral trout and groper, with whitetip reef sharks resting on the sand and rays gliding between them. Clownfish occupy anemones on the pinnacle tops. Visibility here can be exceptional, reaching 40 m on the best days, which makes the whole lagoon feel like an aquarium.

The standard plan is to visit a pinnacle or two while you are deep, then finish over the wreckage, where the shallow depth gives a long, relaxed end to the dive. Snorkellers can see the wreck from the surface. The history of the vessel is not documented in detail by operators, and it should not be thought of as a wreck dive in the penetration sense – it is a reef dive with an interesting artefact.

For newer divers and photographers it is a very enjoyable combination of structure, fish life and clear water.

Agincourt day boats leave Crystalbrook Superyacht Marina (formerly the Reef Marina) on Wharf Street, Port Douglas, between about 8:00 and 8:30 am. Park in the marina car park or the free all-day street parking around Wharf and Dixie streets; Quicksilver, Poseidon and Calypso also run coach pick-ups from Port Douglas, Palm Cove and northern Cairns beaches. The run to the Agincourt ribbon reefs on the edge of the continental shelf is about 65–70 km north-east and takes roughly 75–90 minutes on the large catamarans (Silversonic is the fastest), longer on small-group boats such as Scuba IQ/Blue Dive.

You gear up on board and giant-stride from the dive deck at a permanent mooring; the skipper picks the sites on the day to suit wind and tide, so a named site is never guaranteed. Boats are back at the marina around 4:30 pm.

Agincourt is an outer ribbon reef on the shelf edge, so it is fully exposed to the south-east trade winds that blow from about April to September. Moorings on the protected western (back-reef) side remain diveable in 15–20 knots, but anything over 25 knots or a 2.5 m+ sea makes the crossing rough and operators may cancel or switch to more sheltered moorings. Calm spells in October–December give the glassiest days and 30 m+ visibility.

The wet season (December–April) brings northerlies, afternoon storms, cyclone risk and occasional reduced visibility after big rain events, although the outer reef is far less affected by run-off than inshore reefs. Marine stingers are present November–May. Tidal currents run along the reef edges and through the gaps between the Agincourt reefs; spring tides strengthen them, so exposed corners are usually dived on the neaps or near slack water.

Descend to the sandy lagoon floor and visit two or three of the pinnacles, circling each from the base at 15–20 m up to the top. Finish the dive over the shallow wreckage at 5–8 m, looking under plates for moray eels, lionfish and cod, and do the safety stop beside the wreck or on a pinnacle top.

Quicksilver Silversonic – daily, 3 dives across Agincourt 1–4; Poseidon (Quicksilver Group) – daily, 3 sites at Agincourt; Calypso Reef Cruises – regular Agincourt days; Scuba IQ / Blue Dive and Tech Dive Academy – small-group day trips several days a week.