Keswick Island on the Great Barrier Reef is on the market for $30 million.

The owner of the island, Keswick Developments, has government approval to turn the island into a residential and tourism resort. Keswick Developments is owned by "friend of the royal family" Edward Dawson-Damer, according to The Australian Financial Review.

The island is 517 hectares, including 400 hectares of national park. The development proposal covers 117 hectares, and expires in 2096.

The development proposal includes a 180-berth marina, and up to 1,000 dwellings accommodating 3,000 residents.

The island is 32 kilometres off the coast of Mackay, and already has an airstrip, roads, a small tourism operation, and basic power and water infrastructure.

Development of the island is estimated to cost another $100 million on top of the purchase price.

The island is expected to attract keen interest from Chinese developers, who are most likely to have the funds and population to make the development attractive. Queensland is already popular with Chinese tourists.

Expressions of interest close in August.

Queensland's South Molle Island is also on the market.

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