Lake Eacham is Queensland's best-known freshwater dive: a clear volcanic crater lake ringed by World Heritage rainforest on the Atherton Tablelands, about an hour and a quarter from Cairns. The crater was formed more than 9,000 years ago by violent steam explosions, and the Ngadjon-jii people, who call it Wiinggina, hold oral traditions thought to record those events. No streams flow in or out, and the lake is roughly 65 m deep at the centre, with water levels varying by several metres through the year.

The lake has been protected since 1888 and is now part of Crater Lakes National Park. The North Queensland Underwater Explorers Club describes the dive: entry from the day-use area near the boat ramp, water around 23 °C (cool after a North Queensland summer), visibility typically 5-6 m, and a shoreline of fallen trees that create underwater structure. Archerfish school near the boat ramp, cardinalfish shelter under the submerged trees and redclaw crayfish hide in hollow logs, and submerged timber boats lie at around 25 m.

Saw-shelled turtles are common, and a freshwater crocodile lives in the lake. Introduced predatory fish have devastated the native fish, and only the hardyhead remains of the original species. The club recommends swimming clockwise toward the turtle-viewing platform, careful finning to avoid silt, and an altitude-adjusted computer, since the lake is at around 760-820 m.

It suits Open Water divers looking for something different, and deeper divers for altitude and depth training. Weekday mornings are the quietest time to dive.

From Cairns drive south to Gordonvale and up the Gillies Range Road to Yungaburra (about 1 hour 15 minutes), then follow Lake Barrine Road and Lakes Drive to Lake Eacham, about 6 km from Yungaburra. From Townsville it is about 4.5 hours via Millaa Millaa and Malanda. Use the second car park near the day-use area and boat ramp, which gives the easiest entry and exit and has grass for setting up gear; arrive early as it fills with visitors.

The carry to the water is short. Enter at the boat ramp (rough and slippery) or from the shore beside it. There is no dive shop at the lake; the nearest air fills are in Cairns.

There is no swell or current; the lakes are diveable year-round. Visibility is typically 5-10 m and is best in the drier, cooler months (May-October); heavy wet-season rain and algal growth in warm months can reduce it. Surface water is about 23-27 °C, but it is cooler at depth below the thermocline.

Weekends and school holidays bring crowds of swimmers, so dive early. The lakes are at altitude, so adjust your computer or tables and allow time to acclimatise after driving up from the coast; do not dive and then drive back down over the Gillies or Kuranda ranges without a sufficient surface interval.

Enter at the boat ramp, check buoyancy (freshwater needs noticeably less weight), and swim clockwise along the shore towards the turtle-viewing platform, where the shoreline is more interesting. Follow the fallen trees down the slope to 10-15 m, or to the submerged boats at about 25 m for experienced divers, then return shallower along the shore. Keep off the silty bottom.

Altitude dive: reduce no-decompression limits and use altitude tables or an altitude-capable computer; the deep centre (to about 65 m) is used for deep and technical training – trimix and full technical procedures required beyond recreational depths; cold, dark water below the thermocline.

No commercial operator – dived independently and by clubs such as the North Queensland Underwater Explorers Club (Townsville); commercial diving requires a Queensland Parks permit