Lake Päijänne, lake located in south-central Finland. The lake has an area of 407 sq mi (1,054 sq km) and a maximum depth of 305 ft (93 m). It is about 85 mi (135 km) long and between 2 and 18 mi (3 and 29 km) wide. The lake is broken by thousands of islands. Jyväskylä, at the northern tip of the lake, and Heinola, on a southeastern branch of the lake, are the principal towns. They are connected by ship service with the major city of Lahti to the south of Päijänne via the Vesijärven canal and lake. The Päijänne lake system is drained southward to the Gulf of Finland by the Kymi River. The irregular shoreline around Päijänne is heavily forested and supports important timber operations that use the lake as a means of transport. Numerous villages dot the shore of the lake, and many private villas are located on the quiet bays off its southern end.