El Salvador has 23 volcanoes. Some of the make a terrific hike. El Boquerón is the second widest crater in the country and the walk around its rim is a great and pleasant hike, on the Westernmost limit from San Salvador.
Other hikes at Ecoparque El Espino, on the slopes of the volcano, also available.
Distance from airport (one way): 58 Km.
Walk length: 7 Km.
Check detailed data of the walk here