It covers an area of 3.9 square kilometres (1.5 sq mi).

The lake, also known as Punahau, is an aeolian lake that lies on a sandy plain 2 kilometres (1.2 mi) west of Levin and 5 kilometres (3 mi) from the coast of the Tasman Sea.

The lake was once surrounded by podocarp forest as the centre of a rich wetland ecosystem.

In the 1820s the Muaūpoko were attacked by Te Rauparaha and the Ngāti Toa.

This has contributed significantly to the current eutrophic state of the lake.