Lake Rotoiti is the name of two lakes in New Zealand, one in the South Island and one in the North Island. Rotoiti is Maori for little lake.

Lake Rotoiti, Nelson

The South Island's Lake Rotoiti lies within the borders of Nelson Lakes National Park. It is fed by the Travers River. The greatest depth is 82 metres and is surrounded by beech forest. Saint Arnaud is a small community at the northern end of the lake. The water from the lake exits into the Buller River.

Tramping tracks circle the lake and a water taxi travels the length of the lake to ferry trampers to and from the tracks at the head of the lake.

The lake has introduced trout which attract recreational fishermen.

Lake Rotoiti, Bay of Plenty

The North Island's Lake Rotoiti is the second in a chain of lakes formed in volcanic caldera to the north of Lake Taupo. It is close to the northern shore of its more famous neighbour, Lake Rotorua, and connected to it by a short channel. It drains to the Kaituna River, which flows into the Bay of Plenty.