Cannons – sometimes 'Canons' on local lists and 'Gerhard's Canons' in Underwater Australasia's coverage – is an easy, relaxed dive that the official Cocos tourism listing notes is 'often paired' with a visit to Direction Island. The depth range is 14–22 m. The name comes from a group of old cannons lying on sandy patches between small Porites coral colonies.

Diveplanit explains the local belief that they are surplus cannons dumped as ballast by copra-trading ships, and notes that the cannons are 'really just a sideshow' to the reef. The fine sand under the ledges supports spotted garden eels and white-cap partner gobies sharing burrows with shrimps, and octopus, moray eels and flutemouths work the patches. Underwater Australasia lists Indian and titan triggerfish, fusiliers, surgeonfish, parrotfish, gold-spot emperors, blue-striped and midnight snapper here; titan triggerfish nest in summer and can be territorial.

The endemic Cocos pygmy angelfish is regularly found here. What made the site famous, though, is the large wildlife: Cannons was the home range of Kat, a male dugong that for years approached divers closely, and dolphins and manta rays are regularly seen passing through. Encounters with the dugong were never guaranteed, and divers should check with Cocos Dive on current sightings rather than assume he is still present.

The combination of history, sand-dwelling macro life and a chance of big animals, in calm and moderate depths, makes Cannons suitable for all levels and a reliable choice when conditions elsewhere are poor. It sits among the other northern-rim sites – Two Ridges, Fan Wall and Cable Bommie are all close by – and the boat usually moves on to the Direction Island beach afterwards. Please don't handle the cannons; they are historic relics, and the coral colonies around them are fragile.

Fly to West Island on the twice-weekly Virgin Australia service from Perth (usually routed via Christmas Island; allow 7–10 days on the islands to absorb weather and flight delays). Cocos Dive collects divers from West Island accommodation in the morning (pickup around 8 am, departure about 9 am) and runs its boats from West Island into the lagoon. These sites lie along the northern rim of the atoll near Direction Island, at the north-eastern side of the lagoon around Port Refuge.

The boat crosses the lagoon from West Island to reach them, and they are conveniently paired with the lunchtime surface interval on the beach at Direction Island (eco toilets and shelters, no shops). Live-boat drops or moorings; no shore access.

Cocos has two seasons. The south-east trades blow steadily from roughly April/May to October, often 15–25 knots, which chops up the lagoon and pushes swell onto the eastern and southern outer reefs; divers are then kept to sheltered sites. The doldrum season (November to March/April) brings lighter, variable winds, flatter seas and the widest choice of outer-reef sites, and is the best time to dive, though it is also the tropical cyclone season and squalls pass through.

The northern-rim sites near Direction Island catch tidal flow through the passage at Port Refuge; the incoming tide brings clear ocean water and upwelling along the drop-off, the outgoing tide carries lagoon water out and lowers visibility. In strong south-east trades the lagoon crossing is choppy and wet but these sites are partly protected by the atoll; big northerly swell, uncommon, closes them. Cannons is one of the calmest sites and is dived through most of the year.

Descend onto the sand near the cannons at 14–18 m, inspect the cannons and the Porites colonies around them, then move slowly across the sand patches and under the ledges looking for garden eels, partner gobies, octopus and morays. Keep watching the blue for dugong, dolphins and mantas. Finish in the shallows for the safety stop.

Cocos Dive (Dieter Gerhard, West Island, operating since 1990) is the only scuba operator on the islands and the only way to dive this site. It runs seasonal two-dive day trips with lunch and a surface interval on Direction Island, maximum 10 divers per trip; sites are chosen on the day according to wind, tide and diver experience. Trips book out well ahead and courses are currently suspended, so arrive certified.