great britain lies on the european continental shelf, part of the eurasian plate. situated off the north-west coast of continental europe, it is separated from the mainland by the north sea and by the english channel, which narrows to at the straits of dover. it stretches over about ten degrees of latitude on its longer, north-south axis and occupies an area of , excluding the smaller surrounding islands. the north channel, irish sea, st george's channel and celtic sea separate the island from the island of ireland to its west. the island is physically connected with continental europe via the channel tunnel, the longest undersea rail tunnel in the world, completed in 1993. the island is marked by low, rolling countryside in the east and south, while hills and mountains predominate in the western and northern regions. it is surrounded by over 1,000 smaller islands and islets. the greatest distance between two points is (between land's end, cornwall and john o' groats, caithness), by road.