North and South Twin Lakes are two nearly identical natural lakes in Deschutes County, Oregon. Both were formed around 20,000 years ago when a rising magma reservoir reached groundwater, creating violent steam explosions. Two craters were formed, later filling with water. The Twin Lakes have surprisingly calm winds compared to other Cascade Lakes. South Twin Lake is completely tree-lined except for the beach day-use area. Water levels vary little over the season. The lake is rich with weedbeds.