Bogs
About 10 000 years ago when the mainland ice receded Great-Endla Lake covered almost 3500 hectares of the Upland slopes. As the climate became warmer, swamps began to form in the lowest parts of the lakes. The 6 lakes of the nature reserve – Endla, Sinijärv, Männikjärv, Tulijärv, Kaasikjärv and Sinilaugas – are relict lakes of the Great-Endla Lake.