The small river Losenice is the right tributary of the Otava river. Its romantic valley is a favourite area for tourists.

The river springs about 1.5 km north-west of Přilba mountain (1,215 m) in an elevation 1,118 m a.s.l. The river forms the natural border of the National Park Šumava (Bohemian Forest) all the way. The remains of the primeval fort Obří Hrad (Giants' Castle) can be seen near the Losenice river below Popelní Hora mountain. The confluence with the Otava river is about 3 km behind the fort, near the small village Rejštejn.

The Losenice river is only 15 km long and it runs downhill from the spring to the mouth with the difference of height 560 m. The river basin is 54.5 square km large.

A lot of remains of former gold-washing - placers - can be seen along the river on both banks.

The red marked path leads along the river from the small town Kašperské Hory by the settlement Popelná in the direction of Churáňov mountain. The way from Popelná to Kašperské Hory is about 10 km long. The road from Rejštejn to the settlement Červená goes along the watercourse too.