ONE SUMMER day about 30 years ago, a German tourist went boating on Lake Nerrigorang, part of the Thirlmere Lakes system in what is now part of the Blue Mountains World Heritage Area, south-west of Sydney.

Apparently overcome with joie de vivre, the man began to yodel energetically, whereupon his false teeth popped out and vanished into the water.

Illustration: Matthew Martin

Despite repeated dives by the man and his friends, the missing articles could not be found, and the toothless tourist returned to Germany, crestfallen.

The tale would have remained of strictly local interest for evermore, but the world around Thirlmere Lakes has changed since the 1980s. Most of the lakes have now dried up and, where people once boated, there is now grassland and cracked peat.