Lava Caverns

From the Introduction:

A hot and dry wind howls around you, fed by the heat of the lava flowing in many small channels not too far below you feet. These lava flows separate many small islands of rock, flowing around them, occasionally flowing down a small lava fall. Most of these glowing rivers of molten stone are narrow enough to be crossed by a hearty jump and the rock islands are dry and solid providing for good footing, but the consequences of failure or a single missed step are most dire.