On the southern end of Black Rock the reef drops away quite dramatically to about 15 metres. The best place to anchor is on the western side of the southern end, just 20 metres or so to the north of the point and 20 metres off the rock. The GPS marks for this anchorage are 35° 46' 39"S 150° 14' 45"E (note that all my GPS Readings are using AUS66 - if you use any other datum, you will need to convert the reading - see my GPS Page for more details).

Dive site diagram I drew in early 1990s

You anchor on a rocky bottom. Descend to the bottom (about 10 metres) and swim over to the wall. Follow this to the south and you will come across a small gutter. Keep an eye on the surface and you will soon see that the white water of the waves crashing on Black Rock disappears and you have passed the rocks end. A few metres further on a large boulder blocks the gutter. Swim to the east, up and over the wall that goes up to four or five metres.

Dropping over the ridge brings you right into a huge bowl or "amphitheatre". This is the vertical entrance/exit to The Arch. Go to the bottom and you will see the darkness of The Arch. Swim towards it and you will be able to see daylight on the other side. The Arch is quite long, maybe almost 10 metres at its thickest point, although it is very low. To you left there is a cave that extends back under the arch under Black Rock. There is normally pretty good fishlife under The Arch, especially in the cave. Normally cuttlefish can be seen here as well as friendly blue groper. The depth here is 13 metres or so and the bottom is a combination of sand and small rocks.

Under The Arch there are some magnificent patches of yellow commensal zoanthids while in the bowl there are sponges, gorgonias and sea squirts on the walls.

The depth increases a bit here to 15 metres and by turning around you can see immediately why the site got its name. Keep following the wall to your left and you will see a long, low cave that runs back under Black Rock. You can enter this but beware that not only does it silt up very easily (there is no way to get lost), you must be wary of wobbegongs lying in wait for a diver!

You can follow the wall to the north for about 40 metres and you will see another cave. This also runs back under Black Rock and is quite large. In front of the cave there are some small rocks and last time I dived here there was a small eastern blue devilfish under one of them. Turn around here and go back to the south. When the wall turns to the west, swim across the sandy bottom (with some larger rocks) and rejoin the smaller wall on the eastern side of The Arch. There are a couple of small caves in this area as well as large boulders off the main reef. You can stay in this area for a while and return to the bowl via The Arch by either following the wall to the north all the way or for a distance and then going over the shallower reef straight to the bowl.

Return to you boat by ascend over the western side of the bowl and retracing your steps. The maximum depth on this dive is about 19 or 20 metres (off the wall) and the visibility is normally pretty good. Fishlife is also quite good, with plenty of blue groper around. An excellent dive.