Here are found pools and springs of every degree of heat.

Some are boiling cauldrons into which the unwary fall now and again to meet a death terrible, yet--if the dying words of some of them may be believed--not always agonizing, so completely does the shock of contact with the boiling water kill the nervous system.

Many pools are the colour of black broth.

Foul with mud and sulphur, they seethe and splutter in their dark pits, sending up clouds of steam and sulphurous fumes.

Others are of the clearest green or deepest, purest blue, through which thousands of silver bubbles shoot up to the surface, flash, and vanish.