Fontaine de Vaucluse
The village of Fontaine de Vaucluse is squeezed into the sharp end of a narrow valley and takes its name from the beautiful and mysterious spring feeding the river Sorgue.
This spring comes from deep underground - nobody knows how deep.
In the 50s, Jacques Yves Cousteau came with a submersible to explore the depths but did not find the bottom. Since then a probe has made it to a sandy bed at a depth of 308 metres (1010 ft) but the spring itself comes from somewhere even deeper.
It is said that all the rainwater from the Luberon and other surrounding mountains comes out of this one source, making a catchment area of 1100 square km (425 sq. miles).
For most of the year all you can see is a deep blue pool of water at the bottom of towering cliffs. But during spring or very heavy rainfall it lives up to its name, with water gushing out at 200m3 (52,000 gallons) every second - this is one of the largest springs in the world.
This extraordinary phenomenon forms the crystal-clear Sorgue river, which soon turns a startling emerald, and it's this vivid hue that dominates the town of Fontaine de Vaucluse.
The spring and the beautiful Sorgue river have made the Fontaine de Vaucluse a tourist trap, and souvenir stalls line the walk up to the source (although it must be said that if you are after souvenirs, they are quite good). Go early morning, late afternoon, or simply out of season if you want to avoid the crowds.