A few rough scramble routes drop from the rim into the crater itself, a 250-metre descent through loose volcanic scree. There is no official trail and KWS asks that you go only with a licensed guide and a ranger escort — the rocks are loose, the route is hard to find on the way back up, and there are buffalo on the crater floor.
For most visitors the view from above is enough, but if you do go down you walk through a small forest of acacia, candelabra euphorbia and grassland that fills the entire caldera. Allow a long day; six hours' walking minimum plus the descent.