Pig Island – officially Bass Islet – is the most offshore of the Five Islands and, in Michael McFadyen's words, its northern and eastern sides are 'very good' diving. The south-eastern site is a rocky bottom scattered with large boulders where a small wall runs first north-east and then north along the island's seaward face. The reef steps up from about 25 m to 18 m, and the kelp line sits above that.

What sets Pig Island apart from the inner islands is the density of fixed life and fish. The wall and boulders are thick with sponges, sea tulips and gorgonians, and there is an unusual amount of lace coral (bryozoan) for this coast. Huge schools of ladder-finned pomfret, nannygai and silver sweep hang off the wall, with trevally and yellowtail above them. Blue groper and combfish work the reef, moray eels peer from cracks, rays rest on the sand and wobbegongs tuck under the boulders. Giant cuttlefish are common, especially in the cooler months.

The dive is simple to navigate: out along the base of the wall, back along the top. At 20–25 m it is best suited to Advanced divers, and air consumption and no-deco time rather than navigation will usually end the dive. Because it is the most exposed of the island sites it needs a calm day, and it is often combined with the northern end of the same island or with Martin Island. For Wollongong divers it offers the kind of colourful wall diving that most people associate with Jervis Bay, only 15 minutes from the ramp.

Launch from the Port Kembla boat ramp in the Outer Harbour (behind the steelworks; large car and trailer park, toilets). Wollongong Harbour's ramp (Belmore Basin) is closer to the northern islands but suits only small boats in calm seas. From Port Kembla steer out through the harbour entrance, keeping clear of the shipping channel, and head for the island; the run is 10–15 minutes in a small boat.

Pig Island is the furthest of the islands from Port Kembla, about 4.3 km from the ramp. Run to its southern end and then up the eastern side, 30–40 m off the rocks; use the sounder to find where the bottom rises from 25 m to about 18 m and anchor there (34° 27.955' S 150° 56.786' E).

The Five Islands sit in open water off Port Kembla and are exposed to all swell, but the islands themselves give lee on one side or the other: dive the northern ends in southerly swell and the southern ends in north-easterly conditions. Boats generally want less than about 1.5–2 m of swell and winds under 15 knots for the short run out of Port Kembla Outer Harbour; Wollongong Harbour's ramp is suitable only for small boats in calm seas. Visibility is often better than the inshore beaches, but drops after heavy rain when Lake Illawarra, Allans Creek and the harbour flush brown water out.

Best visibility is usually late autumn to early winter; winter westerlies produce flat seas. The south-eastern side of Pig Island is the most exposed of the island sites – dive it only in north-easterly or westerly weather with small swell.

Descend to the base of the small wall at 20–25 m and follow it north-east, then north as it turns. At half air or no-deco limits, rise to the top of the wall near the kelp line and return along it to the anchor at 12–15 m, finishing with a look through the kelp.

United Divers (Fairy Meadow, Wollongong) runs boat dives to the Five Islands from Wollongong Harbour/Port Kembla when numbers and weather allow; Expedition Dive (Sydney) runs seasonal seal trips (June–Oct/Nov); otherwise private boats and clubs.