Canal Rocks is one of the best-known landmarks on the Capes coast: a line of granite outcrops cut by narrow channels through which the ocean surges, crossed by a footbridge. For divers, marinelife.org.au describes a series of limestone reefs heading seaward in 5-20 m with a sponge garden, gutters full of fish and invertebrates, and western blue groper, dhufish, harlequin wrasse and pelagic fish. Boat access is recommended, although experienced swimmers can reach some reef from shore, and the sheltered north side near the boat ramp is an easier alternative. It is safe in low seas and very rough and surgy in swell.

The combination of granite canals and limestone reef gives varied topography, and the outer reefs, being less visited, hold good fish life. Stingrays gather around the boat ramp. The Honeycombs, a limestone outcrop with ledges and caves 400 m north-east, and the offshore Indicators reefs are listed separately.

The site suits Open Water divers with their own boat on a calm day and experienced shore divers on the north side. The canals themselves are dangerous in swell and should not be swum. It is one of the few places on this surf coast with a boat ramp giving direct access to reefs.

The Capes coast between Cape Naturaliste and Cape Leeuwin faces the Indian Ocean and is famous for its surf, which is exactly what makes diving here so condition-dependent. Long-period south-westerly groundswell can arrive on calm, sunny days, and the regional ocean-safety guide advises observing a site in different conditions before diving it, never diving alone and flying a flag near boat ramps.

From Yallingup drive south on Caves Road and follow Canal Rocks Road to the car park and boat ramp (about 10 minutes). Launch small boats at the Canal Rocks ramp for the outer reefs. Shore divers enter on the sheltered north side near the ramp, keeping clear of boats.

The famous canals and footbridge are beside the car park. The nearest full-service dive shop for fills and hire is Swan Dive in Busselton; there is no dedicated dive shop in Margaret River or Augusta, so bring filled cylinders.

Safe in low seas but very rough and surgy when swell is running (marinelife.org.au); a south-west snorkel guide describes the canals as 'not for the faint-hearted'. Dive only on flat days with easterly winds, typically summer mornings. General pattern on the Capes and Leeuwin coast: summer mornings often have light easterly (offshore) winds before a south-westerly sea breeze, and long-period south-westerly groundswell can arrive on otherwise calm days; winter fronts bring big swell and north-westerly winds.

Check the Bureau of Meteorology swell forecast, not just the wind.

Boat divers anchor off the outer reefs and follow the limestone ridges seaward through gutters and the sponge garden at 10-20 m; shore divers stay on the sheltered north side near the ramp at 5-8 m. Agree a turn pressure before descending (half gas, or a third where current is likely), carry a DSMB, and make a 3-minute safety stop at 5 m.

No regular dive operator; private boats and experienced local shore divers; Oceania Experiences runs snorkel tours on the coast. Nearest dive services: Swan Dive (Busselton/Port Geographe) for fills, hire, nitrox and charters; no dive shop in Margaret River or Augusta.