Lake Lacha (Russian: Ла́ча, Ла́че) is a freshwater lake, located in the south of Kargopolsky District of Arkhangelsk Oblast in Russia, 7 kilometres (4.3 mi) south of the town of Kargopol. It is the largest lake in Arkhangelsk Oblast, with a surface area of 334 square kilometres (129 sq mi) and a basin area of 12,600 square kilometres (4,900 sq mi).