All three then abseil down to the lava lake, despite extreme heat and toxic gases, to take samples.

It has erupted twice in the past 50 years, most recently in 2002, and contains the world's largest continually active lava lake.

In 1924 the lava lake emptied when the walls of the crater cracked and collapsed and filled with water that turned to steam.

It contains an active lava lake, with an episodically overturning crust.

A recent very low elevation of the lava lake was recorded at about 2700 m.