Wallis Lake, an open and trained wave dominated barrier estuary,[1] is located within the Mid-Coast Council local government area in the Mid North Coast region of New South Wales, Australia.

Drawing its catchment from within Wallingat National Park and the Wallamba River, Coolongolook River, and Pipers Creek, Wallis Lake has a catchment area of 1,197 square kilometres (462 sq mi) and a surface area of 99 square kilometres (38 sq mi).

[2] When full, Wallis Lake covers an area of around 10,000 hectares (25,000 acres),[5] is approximately 25 kilometres (16 mi) long,[3] with a width of 9 kilometres (5.6 mi).

[4] Hadleys Island lies within Wallis Lake, near the confluence of the Wallamba and Coolongolook rivers.

The waterways surrounding Wallis Lake are well known for oyster production.