The United Kingdom of Great Britain and Northern Ireland (commonly known as the United Kingdom, the UK, or Britain) is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of the island of Ireland, and many small islands. Northern Ireland is the only part of the UK with a land border with another sovereign state, sharing it with Ireland. Apart from this land border, the UK is surrounded by the Atlantic Ocean, the North Sea, the English Channel and the Irish Sea. Great Britain is linked to France by the Channel Tunnel.