Located in the Andes, Lake Menendez is Y-shaped, of glacial origin, and occupies two narrow valleys between glaciated peaks.

[2] Near the middle of its 26 kilometres (16 mi) length the lake divides into two arms, running at right angles to each other, one continuing northwest, the other turning southwest.

Flowing into Lake Menéndez are several small streams originating in the snowfields and glaciers along the border with Chile, 10 kilometres (6.2 mi) distant.

[4] The most extensive forests of rare Alerce trees in Argentina are located at the tips of the two arms of Lake Menéndez.

[5] The largest known Alerce tree in Argentina is on the northwest arm near a boat pier called Puerto Sagrario.