Niue is an elevated atoll shaped like a two-tiered wedding cake with two terraces rising from the sea. It's one of the largest uplifted coral islands in the world (though 1,196-square-km Lifou in New Caledonia is much bigger).
The lower terrace rises sharply, creating the 20-meter coastal cliffs that virtually surround the island. Inland, a second terrace rises abruptly from this coastal belt to a central plateau some 60 meters above the ocean.
According to Professor Patrick Nunn of the University of the South Pacific, the uplifting continues and half a million years from now Niue will be 50-70 meters higher than it is today.
A fringing reef borders much of the coast, but in places the ocean breakers smash directly into precipitous cliffs. Faulting during the island's uplifting has created the chasms and crevices that are Niue's greatest attractions. Water dripping from their ceilings has added a touch of the surreal in the form of stalactites and stalagmites.
Cruise ships and yachts sailing between the Cook Islands and Tonga sometimes stop for snorkeling at Beveridge Reef, 200 km southeast of Niue and a possession of the country. Beveridge's horseshoe-shaped lagoon is easily entered through a pass on the west side. Like an oasis in the desert, this flourishing ecosystem is surrounded by vast expanses of open sea.