Mount Gambier's big-ticket item is the luminous, 75m-deep lake, which turns an insane hue of blue during summer. Perplexed scientists think it has to do with calcite crystals suspended in the water, which form at a faster rate during the warmer months. Consequently, if you visit between April and November, the lake will look much like any other − a steely grey. But in January, wow! The surface of the water is 20m below central Mt Gambier's street level.

Aquifer Tours runs hourly tours, taking you down near the lake shore in a glass-panelled lift, via an 80m tunnel. Or you can just wander around the rim of the lake along a 3.6km trail.


Lonely Planet's must-see attractions

Nearby attractions

1. Cave Gardens

1.23 MILES

This is a 50m-deep sinkhole right in the middle of town, with the odd suicidal shopping trolley at the bottom. You can walk down into it, and watch the…

2. Riddoch Art Gallery

1.28 MILES

If Mount Gambier's famed Blue Lake isn't blue, don't feel blue − cheer yourself up at one of Australia's best regional galleries. Passionately curated,…

3. Lady Nelson Discovery Centre

1.56 MILES

The Lady Nelson Discovery Centre (access via the visitor information centre) features a replica of the historic brig Lady Nelson, the sailors aboard which…

4. Umpherston Sinkhole

1.79 MILES

This ivy-hung hole-in-the-ground was once a retreat from the summertime heat on James Umpherston's long since subdivided estate, now surrounded by…

5. Engelbrecht Cave

1.83 MILES

A rubbish dump prior to 1979, this meandering cave system runs beneath Jubilee Hwy and 19 local houses! Tours last 45 minutes and take you down to an…

6. Port MacDonnell Maritime Museum

14.83 MILES

Around 40 ships have sunk along the wave-ravaged Port MacDonnell coast since 1844. The Port MacDonnell Maritime Museum is a barnacle-encrusted trove of…

7. Princess Margaret Rose Cave

15.26 MILES

Opened to the public in 1940, this limestone cave with surreal, gleaming calcite formations remains one of Australia's finest show caves. It can only be…

8. Lower Glenelg National Park

15.67 MILES

Hidden away in Victoria's far southwestern corner is one of the state's most scenic national parks, of which the Glenelg River is the most prominent…