The Tarsar Lake or Tarsar is an almond-shaped, oligotrophic alpine lake situated in the meadows of Aru, in the Anantnag district of Jammu and Kashmir. The Tarsar Lake is dominated by the peaks of the Kolahoi mountain massif some 20 km to the east. The lake is separated by a mountain with a minimum peak elevation of 4,000 metres (13,000 ft) from another lake of the same nature known as Marsar Lake, which is in the vicinity of Dachigam National Park. Together these two lakes are referred to as the twin sisters. The 16th-century Kashmiri ruler Yusuf Shah Chak mentioned the twin lakes in his poetry, writing to his beloved.
The Tarsar Lake is drained by an outlet stream which falls into the Lidder River at Lidderwat, 15 km to the east. Being the nearest seasonal settlement, Lidderwat is located on the trek route to the lake from Aru, Pahalgam. Due to the high altitude, the weather is unpredictable. Precipitation is frequent. The temperature rises to the maximum of 20° C during the day and falls to a minimum of 8° C during the night.