Puula (or Puulavesi) is a lake in the Kymi River area in the Finnish municipalities of Hirvensalmi, Kangasniemi and Mikkeli. Puula is 94.7 metres (311 ft) above sea level, the area is 331 square kilometres (128 sq mi), and it is 62 metres (203 ft) deep at its deepest point, located near Porttisalmi at Simpiänselkä, which is the biggest open area of the lake. Two big lakes Suontee and Puula were one lake until year 1854, when the water level was lowered 2.5 meters. This has brought up geological stacks, which are formed by water.