The Canoe Barge is the outermost of the Long Reef barges, 3.5 nautical miles off the headland according to Sydney Dive Charters, and it takes its name from its shape: instead of the blunt, square ends of a standard hopper barge, both bow and stern taper to a point like a canoe, a design used for towed barges that had to be handled in a seaway. The operator describes it as fully intact, with deck winches still in place, and singles out the 'large schools of jewfish' frequently found in its hold as the reason to dive it. Its history is otherwise undocumented; it was presumably one of the Maritime Services Board or contractor hulls disposed of on the artificial reef ground between 1976 and the mid-1980s.

It lies on sand at 45–51 m, the deck around 45 m, and because it is intact and well out on the clean-water side of the reef ground it is one of the more photogenic of the barges, with sponges and anemones on the winches and rails and kingfish patrolling above. The hold is the feature: on a good day it is a moving wall of mulloway, and looking in from the hatch coaming without descending into the silt is the recommended approach. Bastard trumpeter, bullseyes and nannygai are the other regulars.

Distance puts it at the end of the technical charter's range; the run is close to an hour from Manly, surface current is more likely than on the inshore wrecks, and the dive is strictly a decompression profile on trimix or well-planned nitrox with a drifting station. It suits experienced technical divers completing the Long Reef set, and it is a fish dive as much as a wreck dive. As with Barge 656, Sydney Dive Charters' page is the only published account and the position is held by the operator.

Boat only. Technical charters and private boats launch from Roseville Bridge (Middle Harbour), Rose Bay or Little Manly and run 45–60 minutes north past Dee Why to the Long Reef artificial reef ground 4–6 km offshore, or from the Pittwater ramps/Careel Bay Marina and run 40 minutes south around Barrenjoey. The barges lie on a flat sand plain and can only be found by GPS and sounder; the shot must be dropped on the structure.

Drifting decompression station with a following boat.

Open water 4–6 km offshore with no lee: swell over 1.5 m or wind over 15 knots from any direction makes the shot and the long deco hang unsafe, and surface current from the East Australian Current can run hard while the bottom is still. Best visibility (15–25 m) from May to September; summer brings warm surface water, plankton and a thermocline. Avoid the days after heavy rain when the lagoon outflows dirty the inshore layer.

Descend to the deck at about 45 m, examine the deck winches and the pointed 'canoe' bow and stern, look down into the hold for the jewfish school without entering, circuit the hull at 50 m, and return to the shot for staged decompression.

Decompression dive: trimix or air/EANx with 50%/100% deco gases, 20 minutes bottom time for 30–50 minutes of stops; twinset or CCR with bailout; reel and line for any penetration; silt inside holds. Sydney Dive Charters requires Tec 40/T1 and 100 logged dives.

Sydney Dive Charters – Tec 1 charters (Thursday/Sunday programme from Little Manly ramp, Rose Bay wharf or Careel Bay Marina) on demand; otherwise private boats and technical dive clubs. A few visits a year.