Maipo is located within the Diamante Caldera, a feature of about 15 km by 20 km size that is about one-half million years old. It rises about 1,900 m (6,230 ft) above the floor of the caldera. Immediately to the east of the peak, on the eastern side of the caldera floor, is Laguna del Diamante, a picturesque lake that formed when lava flows blocked drainage channels from the caldera in 1826. The Diamante Caldera erupted 450 cubic kilometers (108 cu mi) of tephra, 450 ka.
The region's climate is transitional between the drier Mediterranean climate of the peaks to the north and the cold, moist climate of Chilean Patagonia. Hence, while less glaciated than Patagonia, it has more permanent snow (on the wet, Chilean side) than peaks of similar elevation to the north.