Popocatépetl is southeast of Mexico City, from where it can be seen regularly, depending on atmospheric conditions. Until recently, the volcano was one of three tall peaks in Mexico to contain glaciers, the others being Iztaccihuatl and Pico de Orizaba. In the 1990s, the glaciers such as Glaciar Norte (North Glacier) greatly decreased in size, partly due to warmer temperatures but largely due to increased volcanic activity. By early 2001, Popocatépetl's glaciers were gone; ice remained on the volcano, but no longer displayed the characteristic features of glaciers such as crevasses.