I was asked the other day if I had dived on north head leading out of Sydney harbour. Well, yes. This is a very popular dive site in the summer months when the afternoon NE winds blow as the area is protected by the high cliffs and usually the sea is very flat here in those conditions. The water here in true summer when this occurs is often very green due to warmer water, enriched nutrients and algae blooms. However, it Is not unusual to find a thermocline with clean, clear (and sometimes very cold) water below. Also it is best done on an incoming tide as the outflow from Port Jackson and the Parramatta River sweeps along this edge.
The dramatic sandstone cliffs are unfortunately not repeated in vertical walls under the water but rather the topography is generally slopping. The high point is the fixed or benthic life with many types of sponges, bryozoans, ascidians and corals. Regrettably, it is often in shade so can be quiet dark. So, my tip is to appreciate the colour take a torch.
A typical dive here will see us anchor in around 14 meters of water as this zone has many large bare looking boulders that are actually covered in pink rock algae. All the gaps and crevices give masses of locations to which a reef pick can attach and for fish to hide. The dive plan is usually to meet up at the anchor then head down the slope as a group.
The best sponge life with lots of sea tulips (Spinerfra) and lace bryozoans is in 16 to 21 metres of water with boulders, small sections of wall and lots of crevices and overhangs to explore. Many will contain cuttlefish, octopus, beardie, bullseyes, lobsters and banded sea perch. On the way down you will naturally also be met by all the usual Sydney Wrasse’s and nudibranchs, along with many types of leatherjacket, red morwong, stripeys, half banded sea perch and old wife’s. Stereotypically your escort will be an eastern blue groper from this point to the end of the dive.
After 22 to 24 meters we encounter some sand patches with a little kelp and lots of bowl sponges in broken reef on a flatter topography. This actually continues down to 27 odd meters and beyond to the middle of the harbour. Have a good look around the deeper kelp areas as you may find a weedy sea dragon or an angler fish amongst the nudibranchs and sponges. A warning, be careful where you put your hands or how close to the bottom you swim as there are some big wobbegongs in residence. Port Jackson and Crested Horn Sharks are also in abundance in season. Unfortunately, at his depth your bottom time will be limited to around 25 minutes if your breathing 21% Nitrox or as its better known air.
The dive is far from over, work your way back up the slope and explore around the area of the anchor. Look in the caves and crevices under all the rocks and you will find many more of the same fish, moray eels and sometimes a Bleaker’s eastern blue devil. Also in this area look up and around, to see huge schools of one spot chromis (puller), common grey sweep, mado sweep, trevally, ladder fin pomfrets and sometimes yellowtail scad and if you are in luck a clown toby or two. If the one spots are down at the rocks and some are grey and some are blue, look for their red egg masses. Also big black rays and yellowtail kingfish are known to pass quickly through this area.
I usually then head up into the shallower area 10 meters or less while extending my bottom time before returning to the anchor. Take the time to appreciate the better light levels up here and the long fin pike and also see what else can be found. There are literally dozens of ships that were wrecked on North Head but alas there is little or nothing to be found except an odd piece covered in rock algae that is not quite a natural shape. On the ascent again, look around as you may be passing through the middle of a huge a school of one spot chromis or yellowtail all out feeding on the rich algae filled water. As it can be very busy here on a summer afternoon my last advice is for safety. Please aim to come up the anchor rope, also carry a safety sausage and/or surface marker buoy and reel and know how to deploy them from depth.