North and South Twin Lakes in central Oregon are a closely matched pair of volcanic maar lakes formed about 20,000 years ago when rising magma met groundwater and violent steam explosions blasted out two craters that later filled with water. Sitting just above 4,300 feet in Deschutes County, they are nearly identical in appearance, though North Twin is slightly larger and deeper than South Twin. Their symmetry comes from explosive geologic forces rather than lava flows. Both are known for unusually calm winds and a quiet, sheltered setting. Fishing has also shaped their recent history, especially at South Twin, which has produced notably large rainbow trout.