The 3383-hectare Reserva Geobotánica Pululahua lies about 4km northwest of La Mitad del Mundo. The most interesting part of the reserve is the volcanic crater of the extinct Pululahua. This was apparently formed in ancient times, when the cone of the volcano collapsed, leaving a huge crater some 400m deep and 5km across. The crater’s flat and fertile bottom is used for agriculture.
The crater is open to the west side, through which moisture-laden winds from the Pacific Ocean blow dramatically; it is sometimes difficult to see the crater because of the swirling clouds and mist. The moist winds, combined with the crater’s steep walls, create a variety of microclimates, and the vegetation on the fertile volcanic slopes is both rampant and diverse. There are many flowers and a variety of bird species.