Mosquito Bay is a small bay at Lilli Pilli on the southern shore of Batemans Bay, directly opposite Black Rock. It has a boat ramp and a pebble beach and is used both as a shore dive and as a novice snorkel site. Spirit Divers rated it Easy with a maximum depth of 12 m, describing a nice little site with lots of marine life and a rocky bottom, best in westerly winds, and reminding divers to watch for traffic from the ramp. The Nature Coast Marine Group lists it among its Batemans Marine Park snorkel sites, relatively sheltered from all but the strongest easterlies, with black rays, kelp-covered rocky ridges, fish life and urchins.

The reef consists of rocky ridges running out from shore, covered in kelp and crayweed, with sand between them. Black rays (smooth stingrays) are a highlight and often rest on the sand. Blue groper, luderick, sweep, leatherjackets, wrasse and bream are common, with octopus, cuttlefish, nudibranchs and sea urchins in the rocks. Weedy sea dragons are occasionally seen in the kelp.

The bay's shelter, easy entry and facilities make it a good choice for new divers and snorkellers, and it is also convenient: the ramp is the closest launching point for the Black Rock boat dives, so divers often do a shore dive here as well. The main hazard is boat traffic from the ramp, so use a dive flag, stay out of the ramp approach and avoid peak launching times. Toilets and a café are close by.

From Batemans Bay drive south on George Bass Drive through Batehaven to Lilli Pilli (about 8 km). Spirit Divers gave the entry near 381 George Bass Drive; the Nature Coast Marine Group notes the car park off George Bass Drive, north of Malua Bay. Park in the boat-ramp car park and enter from the pebble beach or beside the ramp, keeping well clear of launching boats.

There is a picnic table, toilets and a café nearby.

The Nature Coast Marine Group describes the bay as relatively sheltered from all but the strongest easterly winds, and Spirit Divers rated it best in westerlies. Strong easterly swell and north-easterly seas reduce visibility and make entry awkward. Heavy rain turns the water murky.

The boat ramp is busiest on summer mornings and weekends, so dive at quieter times.

Enter on the side away from the ramp, swim out to the kelp-covered rocky ridges and follow them seaward to about 10–12 m. Turn at half gas and return along a neighbouring ridge, surfacing well away from the ramp channel.

Spirit Divers listed Mosquito Bay as an Easy guided shore dive (12 m, best in westerlies); the Nature Coast Marine Group lists it as a novice snorkel site. Beneath the Bay offers guided shore dives in the area.