We left the relative comfort of the boat and stepped on to a moonscape. This was the earth at its most raw, how it must have looked when it was first born.

All around us were piles of rocks (some of startling hues due to its mineral content), steaming vents, and bubbling mud pools. We were given gas masks as the sulphire dioxide (that stinky egg smell) was sometimes overpowering. We really had to follow our guides carefully as none of us wanted to drown in a pool of hot acid.

The most impressive site was the steaming vent, or series of vents. Even though the steam was caused by seawater pouring into the hot crater and something more noxious, it was still frightening. It was like peering into the depths of hell.