Santa Ana Volcano, Ilamatepec, is the highest point in El Salvador at 2,381 metres, in the west of the country above the city of Santa Ana, and its summit crater holds a lake of milky turquoise closer to battery acid than to water, hot enough to top 60 degrees, seen from a rim reached by a two-hour walk from the cloud forest of Cerro Verde. The volcano is active, its last eruption in 2005 throwing rocks and ash down the slopes, and the summit is a set of craters inside craters, each ring the scar of a different collapse and rebuilding, with the one holding the lake barely a century old; the walk starts in dripping cloud forest, thins into scrub and ends on open volcanic gravel where nothing grows, with a guide and police escort in the morning group, and at the top the rim drops away to the water a few hundred metres below, streaked white and yellow where sulphur has crusted along the shore, with steam rising from the vents. The name is usually read as Nahuat for hill of the old woman, though historians have quarrelled over it for a century.
From the rim and from Cerro Verde the view is of Izalco, an almost perfect grey-black cone rising out of green forest, a volcano that grew out of flat farmland from 1770 onwards and erupted almost without pause for nearly two centuries, so that sailors steered by its glow and called it the lighthouse of the Pacific; a hotel was built on Cerro Verde in 1958 for guests to watch the eruptions from their rooms, and the volcano went quiet the year it opened. Below the mountains lies Lake Coatepeque, a caldera lake of deep blue seen from the trail, with weekend houses on its shore. In the dry season from November to April the crater stands clear in the early hours, and through the rains the summit sits inside its own cloud. Santa Ana is a mountain with a pool of acid on top, and the walk to its edge is the country's climb.