Island

An island was a body of land completely surrounded by water.

On Earth
The United Kingdom was composed of the island of Britain, (TV: The Stones of Blood) better known as Great Britain, (TV: Rise of the Cybermen and Ireland, (TV: Tooth and Claw) forming part of the British Isles or British Islands, (TV: Boom Town, Fury from the Deep) which included the Shetland Islands. (TV: Army of Ghosts)

Manhattan was an island part of New York City in the United States of America. (TV: Evolution of the Daleks)

Japan was composed of islands. (TV: Last of the Time Lords)

Azores was a group of islands which included Santa Maria. (TV: The Chase)

The South Island was part of New Zealand. (TV: The Tenth Planet)

Anuta Island was located in the South Pacific. (TV: Resolution)

Irving Braxiatel created a floating island which he dubbed Laputa, stationing it near Venice, Italy in 1609. The Armageddon Convention was held there. (PROSE: The Empire of Glass)

The Fourth Doctor and Leela visited Easter Island in 1872. (PROSE: Eye of Heaven) River Song said the Eleventh Doctor was worshipped there when they visited it. (TV: The Impossible Astronaut)

There was a Silurian colony beneath the Galápagos Islands, which revived during Charles Darwin's visit in 1835. (AUDIO: Bloodtide)

Jack Harkness visited Ellis Island at least twice. The first time was in 1892, where he experienced his second death and realised he was immortal. (TV: Utopia) The second was in 1927, where he met Angelo Colasanto. (TV: Immortal Sins