View of the southern end of Lake Wanaka, looking southeast. The Clutha River can be seen in the distance, and at top left is the southern end of Lake Hawea.

Lake Wanaka is located in the Otago region of New Zealand, at an altitude of 300 metres. Covering an area of 192 km², it is the South Island's fourth largest lake. Its name is Maori, probably originally Oanaka ("The place of Anaka", a local tribal chief).

At its greatest extent, which is roughly along a north-south axis, the lake is 42 kilometres long. Its widest point, at the southern end, is 10 kilometres. The lake's western shore is lined with high peaks rising to over 2000 metres above sea level. Along the eastern shore the land is also mountainous, but the peaks are somewhat lower.

Wanaka lies in a glacial valley formed during the last ice age. It is fed by the Matukituki and Makarora Rivers. Nearby Lake Hawea lies in a parallel glacial valley eight kilometres to the east. At their closest point (a rocky ridge called The Neck), the lakes are only 1000 metres apart.

Numerous small islands (notably Rabbit Island and Harwich Island) are to be found at the southern end of the lake. The only flat land is also to be found at the southern end of the lake, surrounding its outflow into the Clutha River. The towns of Wanaka and Albert Town are situated here.

The lake is a popular resort, and is well used in the summer for fishing, boating and swimming. The nearby mountains and fast-flowing rivers allow for adventure tourism year-round, with jetboating and skiing facilities located nearby.