Back in January 2010 the new desalination plant opened at Kurnell on the southern side of Sydney. This $1.803 billion monstrosity was built despite considerable opposition from the general public. Since then it has not operated more than it has operated as the water was never really needed. As of February 2025, it is allegedly operating (according to Sydney Water), but I have my doubts as you will see from below.

Of course to operate, the desalination plant requires salt water from the ocean and also needs to dispose of the very salty water which is a by-product of the freshwater that is made. As such, two tunnels were built from the land out into the ocean for these. One was drilled from just south of Tabbagai Gap for the inlet and further 700 metres south another was put in for the outlet.

Since then I have wanted to dive the inlet as I had heard reports that it was a very good dive. However, I never got around to doing it till February 2025 when I went out on a boat owned by a member of our dive club.

From Botany Bay, turn south as you exit the bay and travel past The Whale Watching Platform dive site to Tabbagai Gap (which is very obvious). The site is very near here. The GPS mark for the anchoring spot is approximately 34°01'38.352"S 151°13'55.812"E (note that GPS Readings is WGS84 - if you use any other datum, you will need to convert the reading - see my GPS Page for more details). If you run around you will see that the bottom is about 25 metres here and that the inlet structure comes up to about 18 metres. The mark is for the eastern-most inlet (which I will call Inlet 1). Anchor here.

Inlet 2	A gorgonia with Inlet 3 behind

This should put you in the vicinity of the structure which I will describe as follows. There are actually four inlets, all basically identical, lying in an east-west line. They are about 10 or 12 metres across, round, and five or six metres high. They stand a bit higher off the bottom as they are built on a base that seems to have been formed by a concrete filled fabric bag (sort of like a "door-snake") which has been looped to make a circle. Then concrete has been placed inside to make a floor. The structure has then been put together like a clip-lock structure on top.

The inlets have solid walls from the bottom and then a sort of prison bar-like "windows" where the sea water can enter. The bars are far enough apart to enable every large fish or sharks to enter. These bars are removable so they can be cleaned of growth. It looks like they are just slotted into a holding device and to remove, they are winched up by a barge. The top of the inlet at first appears to be one solid mass, but in reality it consists of a removable centre piece. Again, this appears to get winched up as well.

Peta Kirby outside Inlet 3, notice the missing bars	Looking out from inside Inlet 3 as Peta Kirby exits

Inside is the inlet nozzle itself. This seems to have a cover over it which can also be removed. I think this is why there is the circular removable roof piece. See later for how I know this.

Anyway, if you anchor as above, the first one will be visible in any sort of reasonable visibility. When I dived here we had 20 metres so could easily see from one to another inlet. Inlet 1 had very clean bars, so it looks like they had been replaced after cleaning less than two weeks earlier. Inlet 2 is located about 10 or so metres to the west of the first one. In poor visibility, just head west for a short distance. It is about the same depth as the first one.

The actual inlet nozzle inside Inlet 3	Looking up at the roof inside Inlet 3

Inlet 3 is located a bit further away from Inlet 2, perhaps 15 or 17 metres. It is also a bit shallower here. When I dived here, the bars were missing from three of the windows, presumably taken away for cleaning. The roof section was also missing as was the cover for the actual inlet. This meant we were able to go inside the structure.

We explored inside Inlet 3. There was a wobbegong shark on the floor and as I mentioned, the cover over the nozzle had been removed. There was no indication at all that water was being drawn into the nozzle and as I doubt they can shut off one of the Inlets remotely, I came to the conclusion that no water was being drawn in at all.

Looking from Inlet 3 towards Inlet 2	Sea tulips on the side of one of the structures

Once inside whatever structure is open (it seems that one is always open), go up to the roof and have a look. You will see that it is covered in thousands of jewel anemones. There are four or five colours at least, pink, yellow, blue and mixed ones. You can get some very nice photographs here.

Once you are finished, go back outside and head around to the western side. You should be able to see Inlet 4 which is a similar distance away as 1 and 2 are, that is, 10 to 12 metres. The bottom is shallower here, maybe 23 to 24 metres. Go around the inlet and then head slowly back to the east and revisit in turn, 3 2 and 1.

Once back at Inlet 1, go up onto the roof and have a look at it. It is covered in kelp and you can see the attachment points and ropes for when they remove the centre-piece. By now it is probably time to ascend. I was using Nitrox 31% and I hit deco at 35 minutes.

Jewel anemones on the underside of Inlet 3 roof	The connecting piece where the steel bar windows sit

There were lots of fish on this dive, large schools of seapike and yellowtail as well as lots of small leatherjackets and a few octopuses. We even saw a fiddler-ray and the first lot of divers saw a lot of kingfish.

This is a site that I really wish now I had visited 10 years earlier, as it was an extremely enjoyable dive. Unfortunately, currently there are no charter boats that dive this location as far as I know.