Masaya is a shield volcano located 20 km south of Managua, Nicaragua. It is Nicaragua's first and largest National Park, and one of 78 protected areas of Nicaragua. This hosts Masaya caldera, formed 2500 years ago. Masaya continually emits large amounts of sulfur dioxide gas (from the active Santiago crater) and volcanologists study this (amongst other signs) to better understand the behavior of the volcano and also evaluate the impact of acid rain and the potential for health problems.
There is a cross "La Cruz de Bobadilla" on the edge of the crater since the 16th century in order to exorcise the devil.