Mudjimba Island, also called Old Woman Island, is the small rocky island off Mudjimba Beach that you see from almost anywhere on the northern Sunshine Coast. Because divers can always find a side sheltered from the wind, it is the region's all-weather site: the place operators go when the offshore reefs are too rough, and where most Sunshine Coast divers do their training dives.

Sunreef describes a wall running from 16 m up to 5 m, and Weekend Notes coral gardens 'at just two metres deep', with fields of hard and soft coral cut by gullies, ledges, bommies and small drop-offs. The shallow upper reef, at about 3-5 m, is Scuba World's main snorkelling destination, with hard and soft corals, tropical fish, turtles and crustaceans.

It is an excellent macro site. Sunreef lists crayfish, wobbegong sharks, a variety of nudibranchs, cowries, rays and turtles; Scuba Diver Life and PADI add lionfish, hermit crabs, cowries, boxfish, cuttlefish, octopus, mantis shrimp, boxer shrimp, gobies and flatworms. The Sea Slug Forum notes it as a good shallow site surrounded by sand with rock and coral reef, and Weekend Notes rates it ideal for macro photography, with butterflyfish, moray eels, wrasse, angelfish, morwong, surgeonfish, damsels and pufferfish all common.

The island is only about 1.5 km off Mudjimba Beach and is a landmark for the whole northern Sunshine Coast; dive trips stay in the water and do not land on it.

Mudjimba suits new divers, snorkellers, photographers and anyone wanting a relaxed, shallow dive with long bottom times. Experienced divers treat it as a macro dive or a second dive after the Brisbane or the outer reefs.

Mooloolaba's dive boats leave from The Wharf on the Mooloolah River (Parkyn Parade, Mooloolaba), about 1.5 hours' drive north of Brisbane via the Bruce Highway and Sunshine Motorway. Scuba World's shop is about 40 m from its boat, with 100+ free all-day parking spaces nearby; Sunreef departs from the same precinct. Boats run down the calm river, cross the Mooloolah River mouth beside Point Cartwright and head north-east to the reefs – about 15 minutes to the Inner Gneerings and Mudjimba Island.

Private boats can launch at the Mooloolaba (Parkyn Parade/Lions Park) ramps. Mudjimba Island is about 15 minutes by boat from Mooloolaba (Scuba World quotes about 25 minutes from its shop for snorkel trips). Boats moor or anchor in sand on the sheltered side chosen for the day's conditions.

The Mooloolaba reefs are open-ocean sites with no shelter from the south-east trade winds or easterly swell. Operators generally cancel when winds exceed about 20 knots or swell makes the river-mouth crossing and moorings unsafe; they confirm trips by email and text around 3.30 pm the day before. Northerly winds (common on summer afternoons) also make the reefs choppy, so morning trips are more reliable.

Visibility averages about 12 m offshore (range 3-30 m) and is clearest after southerly winds and in winter; it drops after easterly blows and heavy rain. Winter (June-October) brings 19-21°C water, grey nurse sharks and humpback whales; summer (November-May) brings 25-27°C water, leopard sharks and lower visibility.

Descend on the sheltered side of the island to the base of the wall at 12-16 m, follow it with the island on one shoulder, and work back up through the gullies and ledges to the coral gardens at 3-5 m for the last part of the dive and the safety stop. Sunreef plans dives to 50 minutes or 50 bar, whichever comes first.

Sunreef Mooloolaba – double reef dives most days, rotating between Mudjimba Island, Nurse Rock, Hanging Rock and Caves; Scuba World Mooloolaba – reef double dives rotating through the Gneering Shoals and Mudjimba sites; SubSurface Scuba – Sunshine Coast reef double dives.