Wiroa Island, also known as Kohia, is an island in Manukau Harbour, New Zealand. The island is located at the mouth of the Pūkaki Creek, directly southeast of Auckland Airport.

Wiroa Island is located southeast of the Auckland Airport complex and is only connected to the mainland by a narrow, approximately 370-metre-long (1,210 ft) causeway, on which a road leads to the island. The approximately 38.7-hectare (96-acre) island has a length of around 1.4 kilometres (0.87 mi) in a west-northwest–east-southeast direction, and measures around 390 metres (1,280 ft) in a north-northeast–south-southwest direction at its widest point. The island lies less than five metres (16 ft) above the water level of the Manukau Harbour. As the island is a part of the Auckland Airport complex, it is inaccessible to the public.

Historically, Tāmaki Māori used the island to collect red ochre. Its traditional name, Kohia, is a reference to this.

The surrounding area became farmland, and in 1928 the adjacent land on the Māngere Peninsula was used as the Mangere Aerodrome, later being developed into an international airport, Auckland Airport, opened in 1966. During this period, Wiroa Island became a part of the airport complex, and a radar tower was constructed on the island.

A bird habitat was created on the southeastern part of the island, to divert birds away from the airport airfield.

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  Aerial view of Wiroa Island in 1954 before the construction of Auckland Airport
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  Aerial view of Wiroa Island in 1965 during the construction of Auckland Airport