Lake Ellesmere / Te Waihora is a broad, shallow coastal lake or waituna, in the Canterbury region of the South Island of New Zealand. It is directly to the west of Banks Peninsula, separated from the Pacific Ocean by the long, narrow, sandy Kaitorete Spit, or more correctly Kaitorete Barrier. It lies partially in extreme southeastern Selwyn District and partially in the southwestern extension of the former Banks Peninsula District, which now is a ward in the city of Christchurch. The lake holds high historical and cultural significance to the indigenous Māori population and the traditional Māori name Te Waihora, means spreading waters. It has officially had a dual English/Māori name since at least 1938.

Banks Peninsula is a peninsula of volcanic origin on the east coast of the South Island of New Zealand. It has an area of approximately 1,150 square kilometres (440 sq mi) and encompasses two large harbours and many smaller bays and coves. The South Island's largest city, Christchurch, is immediately north of the peninsula.