An entire beach at Punakaiki on the South Island's West Coast has disappeared in under a year, with the loss of 30,000 cubic metres of sand.
West Coast Regional Council rivers and drainage engineer Wayne Moen said the beach immediately north of the blowholes, had dropped 2.5m.
"I've never seen it happen like that before. The whole beach has basically disappeared."
King tides over the weekend threw rocks over the seawall, flooded a motel and demolished a fence.
Mr Moen said the latest results of regular cross-sections taken of the beach showed that 30,000 cubic metres of sand had gone.