Cerro Negro came out of a farm plain in Nicaragua in April 1850, and people watched it happen. It is the youngest volcano in Central America, and from the track in from León it looks exactly like what it is: a black heap dropped into ploughed fields, with no range or foothills to soften it. Nothing has taken root on it in 175 years. The cone behaves oddly for its type: ash comes out of the summit crater, but the lava breaks out of fractures around the base. So the flows lie out on the plain instead of scarring the face, and fresh cinder keeps falling back on the slopes and rebuilding them into a clean black pyramid.
The climb takes forty-five minutes on loose scoria that gives back half of every step, your own sled under one arm. On the last ridge the wind arrives all at once. Then comes the part it is known for: a jumpsuit, a plank of plywood, and a push off down the cinder face with your heels for brakes. It takes a few minutes, and you get to the bottom black from the goggles down. The fastest anyone has gone down was on a bicycle: in 2002 Éric Barone hit 172 kilometres an hour on this ash; the gradient then eased, his front fork snapped, and he finished the descent with broken ribs. From the rim the Maribios volcanoes stand in a line across the plain, each a cone on the same crack in the crust. The crater walls are cooked rust-red, and the fumaroles vent gas measured at up to 325 degrees. In 1992 it put an ash column seven and a half kilometres up and dropped four centimetres on León, twenty-five kilometres away, collapsing roofs across the plain, and more than twenty thousand people were moved out. The last eruption was in 1999. On the rim the ground still comes through your palms warm.