Michael McFadyen's Scuba Diving - Osborn Shoal South West
Although some Sydney divers will tell you that the best dive sites are to be found by diving out of Sydney Harbour or from the northern beaches, divers who have dived from Port Hacking will agree that the ocean off Cronulla and Royal National Park contains far better dive sites. Among the abundant excellent dive locations off this section of the coast is Osborn Shoal.
|A great gorgonia on the wall
at Osborn Shoal South West
Located directly off Cronulla Beach, Osborn Shoal (this is the name preferred by the NSW Geographical Names Board) is one part of the reef that can be found intermittently from Kurnell to Bundeena across Bate Bay. Like Merries Reef further to the north, the top of the shoals is generally flat and covered in kelp, although some parts are covered with sponges. Once you drop off the top, however, things change. On the eastern, northern and southern sides a sharp drop off takes place with the depth going from 12 to 20 or more metres in some spots. On the western and southern sides the reef goes from 11 metres to about 15 to 18 metres or more.
To find the reef, head out of Port Hacking towards a GPS Mark of 34° 03' 40.0"S 151° 11' 05.3"E. Note that all the GPS Readings on my Web Site are taken using AUS66 as the map datum. If you use another datum you may be about 220 metres off the wreck. See my GPS Page for more details and how to convert readings.
When you get near this location, slow down and put your depth sounder on. You will see that the bottom comes up from 18 or 20 metres (depending which direction you come from) to around 11 to 12 metres. Once you are over the shallower section of the reef, do the following. In a southerly wind, head south and drop anchor once the wall is encountered. In a westerly or north-westerly, run to the north-west and drop anchor once you go over the wall. In a north-easterly breeze, run in over the shoals a bit and drop anchor (make sure you put out a good length of anchor rope in case the anchor comes free and drops off the reef top). You should be right on the corner of the reef.
After descending to the anchor, if you are not already on the reef edge, swim to the west or south till you hit the wall. Follow the wall to the north (or west if you are on the south edge), keeping the wall on your right. The most interesting dive is normally to the north. All along this section there are lots of small overhangs and cracks. The walls have plenty of colourful sea tulips (sea squirts) and some nice gorgonias. The depth here is about 17 to 18 metres.
As you go the depth will gradually shallow to about 14 to 15 metres. Do not follow the sand edge, but the main wall. After about 40 metres the sand edge goes off the the west. This needs exploring and once I do, I will update this page. The main reef wall is about three metres at first and varies between this and two metres. There are more cracks and overhangs. There are also quite a few large boulders that are lcoated off the wall. There are also some smaller rocks further off the wall, including some on the sand. The cracks and spaces between the boulders can be home to huge numbers of ladder-finned pomfrets, yellowtail and old wives. There are also lots of luderick.
|A Port Jackson shark swims past
the edge of wall north of the corner
|A large school of ladder-finned pomfrets
in between some of the boulders
After about 15 minutes, turn around and head back the way you came. Once you get to the anchor, head past this and follow the reef to the east. There are some larger overhangs here. Off the reef there are some small rocks. After about 50 metres, the wall becomes less prominent and by this time you should probably head back to the anchor.
Near the corner, on the south side, there are the remains of a small boat. It was a fibreglass hulls, with an inboard motor. There is a section of hull, a stainless steel prop-shaft and what appears to be a bait box.
This is a dive site worth diving and worth some more exploration. As far as I know, no-one divers this spot except members of the St George Scuba Club.