The more than 330 islands of New Zealand provide breeding and nesting sites for huge numbers of sea birds, including gulls, terns, penguins, shags, gannets and albatrosses. Seabird densities on the subantarctic islands are among the highest in the world. The numerous important locations for observing birds include Miranda on the Firth of Thames, an important wintering ground for thousands of Arctic nesting shorebirds, and Farewell Spit at the top of the South Island. Albatrosses are the world's largest seabirds. They normally breed on remote islands and spend at least 85 percent of their lives at sea, well away from land and human view. Renowned ocean wanderers, they travel vast distances from their breeding grounds to feed. The royal albatross, for example, with its massive wingspan of up to 3.3 metres flies an estimated 190,000 kilometres a year. The northern royal albatross breeds on the Chatham Islands and at Taiaroa Head on the Otago Peninsula, one of only two places in the world where albatrosses breed on the mainland.