Black's Reef is a broad reef system in the lee of the Bluff, between the Bluff boat ramp and Wright Island. The Federation describes an extensive reef in sheltered waters down to 14 m, and the Marine Life Network adds that it covers more than 500 square metres, with a series of bommies surrounding the main reef in 8-14 m. The reef is granite and rock covered in kelp and mixed weed, with sponges and invertebrates on the shaded sides of the bommies.

Seadragons are seen regularly, according to the Marine Life Network, which also lists leatherjackets, small rays and blue devils among many others. The bommies give the dive structure and plenty of edges to search, and the sand between them is a good place to look for rays. Because it is close to the Bluff and sheltered from the west, Black's Reef can be a useful alternative to the busier shore dive, particularly for divers with their own boat.

It is shallow enough for long dives and suits Open Water divers comfortable with boat entries. Shore divers can reach it, but the swim is long and crosses an area used by boats heading in and out of the ramp. Like all Encounter Bay sites, it depends on the weather: after several days of northerlies it can be excellent, while southerly swell makes it murky and surgy.

There are no detailed published maps of the reef, so exploring it thoroughly may take several dives. A torch helps to look under the bommie edges, and a reel and surface marker make it easier for the boat to follow if divers drift away from the anchor.

Drive to the Bluff at Encounter Bay, Victor Harbor (about 1 hour 15 minutes from Adelaide). Launch a small boat at the Bluff boat ramp and run a few minutes north-east toward Wright Island; the reef lies between the two. The Federation notes shore access is possible but involves an extensive swim, so a boat is recommended.

Anchor in sand beside the reef and fly a dive flag – the area is busy with fishing boats.

Encounter Bay faces south into the Southern Ocean swell that wraps around Kangaroo Island and Cape Jervis, so Victor Harbor sites are the reverse of the gulf coast: they need northerly (offshore) winds. The best days follow several days of northerlies with low southerly swell, when visibility improves and the swell is blown back; any southerly or south-westerly swell over about 1 m, or strong southerly winds, makes most sites undiveable and stirs up particles. Summer and autumn bring the most northerly days, but good windows also occur in winter ahead of cold fronts.

Tidal currents strengthen around the headlands and islands during large tidal movements. Southern right whales visit Encounter Bay from about June to October – keep legal approach distances. Water is a little cooler than in the gulf.

Black's Reef sits in the relatively sheltered western corner of the bay behind the Bluff.

Anchor beside the main reef, circle it at 10-12 m, then visit the surrounding bommies, searching weed edges for seadragons. Use a compass to return to the anchor.

No regular operator; private boats from the Bluff ramp and occasional club dives.