Kaipara Harbour is a large enclosed harbour estuary complex on the north western side of the North Island of New Zealand. The northern part of the harbour is administered by the Kaipara District and the southern part is administered by the Auckland Council.

By area, the Kaipara Harbour is one of the largest harbours in the world. It covers 947 square kilometres (366 sq mi) at high tide, with 409 square kilometres (158 sq mi) exposed as mudflats and sandflats at low tide.

These treacherous sandbanks shift and change position, and are known locally as the graveyard. The graveyard is responsible for more shipwrecks than any other place in New Zealand, and has claimed at least 43 vessels—some say as many as 110. For this reason, a lighthouse was built in 1884 on the northern arm of the entrance (Puoto Peninsula). It was automated in 1947 and closed in the mid 1950s. The structure still exists and was renovated in 1982–84.