On the rim trail, near the highest part of the southern arc, the path passes a series of small fumaroles where steam still rises from cracks in the rock. They are easy to miss — no signpost — but the air smells faintly of sulphur for a hundred metres, and the rocks immediately around the vents are hot to the touch.
A reminder that the volcano is dormant, not dead. The wider Rift Valley around Longonot still has plenty of geothermal activity, most of which goes into the country's electricity grid via the power station at Olkaria a few kilometres west.