Ponui Island is located in the Hauraki Gulf, to the east of the city of Auckland, New Zealand. It is located to the southeast of Waiheke Island, at the eastern end of the Tamaki Strait, which separates the island from the Hunua Ranges on the mainland to the south.
The island is virtually uninhabited (the population was 9 in 2001), and has an area of 18 km2. It is a popular site for youth camps for organisations such as scouts.
The island is the home of New Zealand's only feral donkey breed, the Ponui donkey.