The Gutter Sponge Gardens is the deeper extension of The Gutter at Bass Point, and it turns a pleasant shallow dive into a more substantial one. After following the gutter's western wall north for about ten minutes, divers strike out across roughly 40 m of sand and scattered rock to a patch of reef where the depth drops to 20 m and soon 22–23 m.

The gardens are dense with sea tulips, sponges and gorgonians in a range of colours, and they are an excellent place for macro life: eastern hulafish hover over the growth, pygmy leatherjackets pick at it, and nudibranchs are common. Cuttlefish and squid move over the sand, and moray eels occupy the reef. McFadyen records a large bull ray and, in 2006, a small angelshark here; sea dragons, red morwong, striped seapike, leatherjackets and bream are all often seen on the way out and back.

The site shares The Gutter's great advantage – shelter from southerly winds, even in a gale – but it asks more of the diver. The depth, the swim across open sand and the distance from the exit mean it is not recommended for inexperienced divers; good navigation (a compass heading north and a reciprocal back) and gas management are important, and a 25–30-minute turn is typical. For Advanced divers it is one of the best shore dives on the South Coast, combining a deep sponge garden with an easy, well-known entry and exit. Nitrox helps extend the time at the gardens, and a torch brings out the colours of the fixed growth.

From Sydney take the M1/Princes Motorway south past Wollongong (about 105 km, 1.5 hours), take the Shellharbour exit and follow Shellharbour Road to the Shellharbour Workers Club, then turn right onto Boollwarroo Parade into Bass Point Reserve. Drive nearly 2 km along the dirt road into the reserve and park at the north-western corner of the car park near the gravel loader for the shortest walk. Cross the grass and rock platform to The Gutter and enter at the most suitable point for the tide.

The northern (Shellharbour-facing) side of Bass Point is protected from southerly winds and swell – even gale-force southerlies – which makes it the Illawarra's reliable shore-diving fallback. It is blown out by north-east swell over about 1 m and by strong nor'easters, which are common on summer afternoons, so summer dives are best done in the morning. Tide is not critical but high tide makes entries and exits over the rock platform easier.

Visibility ranges from 5 m after swell or rain to 15–20 m in winter westerly spells. The reserve gate may be closed on total fire ban days.

Descend in The Gutter and follow its western side north for about 10 minutes to 18 m. Then swim due north about 40 m across sand and rock to the sponge gardens at 20–23 m. After 25–30 minutes start back south, find the wall and follow it into the main gutter, shallowing gradually to the 3 m exit.

Shellharbour Scuba and Photography Centre runs guided shore dives and training at Bass Point most weekends and regular social dives; United Divers (Wollongong) and many Sydney clubs and dive shops also bring groups.