The Kingscliff seawall, in the Tweed Shire in northern New South Wales, is an engineering marvel. It is 300 metres long and 6 metres deep, with a projected cost of between A$3 million and A$5 million. Its depth enables it to be covered in sand. When beach erosion occurs, the wall’s large concrete steps should, in theory, allow the public to carry on using and enjoying the waterfront.