Azores

Hydrothermal activity is common in active volcanic calderas. On the shoreline of the Furnas lake, it is possible to admire boiling mud pools. Above, the mud jet rising in the centre of the pool is strong enough to form a sustained fountain about half a meter high. Note the convective circular motion of the mud around the central fountain.

This fumarolic area offers a ten of water geysers and mud pools, some of which nicely small. Below, boiling mud and gas bubbles produce a nice symphony of puffs and whistles (videoclips bottom of page).