The Kurnell Desalination Plant Inlet is a man-made site with a surprisingly good marine community. The Sydney Desalination Plant at Kurnell was completed in 2010 and draws its seawater through four intake structures on the seabed off Tabbagai Gap, with a separate outlet discharging brine. The four inlets stand in an east–west line about 15–20 m apart.

Each is round, about 10–12 m across and 5–6 m high, with solid walls rising from the bottom and removable 'prison bar' windows through which the water is drawn in. They sit on concrete-filled fabric bases looped to form a circle, and their removable roof sections carry attachment points and ropes. The seabed is at about 25 m, with the tops at about 18 m; Inlets 3 and 4 are slightly shallower at 23–24 m.

Kelp covers the tops, and the underside of the roof overhang is the highlight: thousands of jewel anemones in four or five colours – pink, yellow, blue and others – packed together like a carpet. Around the structures there are large schools of seapike and yellowtail, many small leatherjackets and a few octopuses, and McFadyen has seen a wobbegong on the floor inside Inlet 3, along with kingfish and a fiddler ray on other dives. In February 2025 he had 20 m visibility, enough to see one inlet from the next.

The site suits Advanced divers comfortable at 25 m who can plan a nitrox dive around several separate structures; it is a private-boat dive because no charter currently visits. Divers should treat the intakes with respect: they are working infrastructure, and the windows draw water when the plant is running. Also note that the 2008 construction damaged the reef nearby at Tabbagai Point, a reminder of the site's industrial origin.

Boat only – the Kurnell cliffs are sheer and in Kamay Botany Bay National Park, with no practical shore entry. From Botany Bay, launch at Kyeemagh (Cooks River), Foreshore Road or Bonna Point (Silver Beach, Kurnell), run out past Captain Cook's Landing Place, Inscription Point and The Leap, then turn south along the cliffs; from Port Hacking (Gunnamatta Bay/Tonkin Park or Lilli Pilli ramps) run out past Bass and Flinders Point and north-east along Bate Bay past Cronulla Beach and Cape Baily. From Botany Bay turn south as you exit the bay and travel past the Whale Watching Platform to Tabbagai Gap – about 20 minutes.

McFadyen's approximate GPS is 34° 01.6230' S 151° 13.9472' E. Anchor near Inlet 1 in about 25 m, taking care not to foul the structures, or drop a shot beside it. No charter boats dive it; private boat only.

Exposed open-coast site off Tabbagai Gap, affected by north-east to south-east swell; plan for seas under 1.5 m. Visibility can be excellent – 20 m in February 2025 allowed McFadyen to see from one inlet to the next – but it deteriorates after rain and on big ebbs from Botany Bay. Because the inlets draw seawater continuously when the plant operates, avoid putting hands or gear near the intake windows.

Calm mornings are best.

Descend at Inlet 1 and visit Inlets 2, 3 and 4 heading west (15–20 m apart), then return east revisiting each and looking up under the roof edges at the jewel anemones. Plan the dive on nitrox; McFadyen on EAN31 reached his no-deco limit at 35 minutes. Ascend on the anchor or shot.

Nitrox (EAN28–32) recommended for 30–35 min bottom time. Check for any exclusion zone or Sydney Desalination Plant restrictions before diving.

No regular charter – private boat or dive-club (St George Scuba Club) only