La Balsa Park is the Sunshine Coast's best-known muck dive and one of the most important nudibranch sites in Australia. The park sits at Buddina on the southern side of the Mooloolah River mouth, opposite Mooloolaba (some sources wrongly place it on the Maroochy River). Gary Cobb's nudibranch.com.au diving guide records 'over 700 species of nudibranchs' from the river, and species lists from Nudibranch Central and Nudibranch Domain document dives producing dozens of species at a time.

The dive itself is simple. From the park's staircases you descend the rocky river bank onto a sandy, rubbly bottom with a maximum depth of about 6 m. There are no coral gardens or dramatic structures – the attraction is what lives in the algae, sponges, hydroids and rubble. Scuba Diver Life describes 'thousands of nudibranchs', plus crabs, shrimps, pipefish, cardinalfish, ghost pipefish and octopus; the nudibranch guide adds sea snakes and stingrays. Frogfish, seahorses and cuttlefish are among the critters that make it a macro photographer's destination.

Local etiquette matters. Because many divers are lying motionless over tiny subjects, the guide asks visitors to use frog kicks, avoid vertical finning, not hover 1-3 m above others near dive flags, and never fin over other divers. It warns of stonefish, rays and fortescues, fishing hooks and line, people fishing from the bank, boats and dredging equipment, and states that the boating channel is strictly off-limits.

Tide timing is critical: dive around high water, when clean ocean water floods in and current is manageable. Dive times range from an hour to several hours. It suits every level, especially photographers and anyone with patience.

La Balsa Park is at Buddina on the south side of the Mooloolah River mouth, reached from Mooloolaba by crossing the river on the Nicklin Way/Brisbane Road bridge and following Point Cartwright Drive and La Balsa Parade – about 10 minutes' drive. Park in the La Balsa Park car park beside the boat ramp. The nudibranch.com.au diving guide describes three staircase entries north of the boat ramp: 'Fish Cage' (closest to the ramp), 'Rotunda' (middle) and 'Toilet Block' (furthest north).

Gear carry from the car park is 20-80 m on grass and paths.

La Balsa Park is inside the river mouth, so ocean swell and wind matter far less than tide. The river's range is roughly 1.1-2.2 m, and the nudibranch.com.au guide recommends diving just before and during high tide: on small tides you can start about 3 hours before high water, but on big tides wait until an hour or less before the peak, as the flow becomes too strong. The incoming tide brings clean ocean water; the ebb brings river water and silt, and heavy rain turns the river brown for days.

Strong easterly swell can push surge through the river mouth. Water ranges from about 18°C in winter to 29°C in summer.

Enter at one of the staircases about an hour before high tide, descend the rocky bank to the sand at 3-6 m and move slowly along the edge, searching the rubble, algae and sponges for nudibranchs. Stay well inside the rock wall margin and never enter the boating channel to the west. Turn around before the tide turns and exit at the same stairs.

Dives here are slow and long – one to several hours for dedicated photographers.

Very long, shallow, slow dives – dress warmly and monitor gas; follow local photographer etiquette.

No operator required. Local clubs (e.g. the Underwater Research Group of Queensland) run regular 'nudi shore dives' here; Mooloolaba dive shops supply tanks and gear.