The United Kingdom is located in Northwestern Europe and includes the island of Great Britain, surrounding islands and part of Ireland. The country is surrounded by the Atlantic Ocean, the North Sea, the Irish Sea and the English Channel. The rugged coastline — around 12,500 kilometers long — and surrounding waters, covering important oil and gas reserves, offer the nation protection; particularly from rivals in continental Europe. The United Kingdom's main geographic challenge is the integration of the British Isles. The rugged topography of the islands fostered the development of strong regional identities. Competing regions like Wales, Northern Ireland and Scotland make it difficult to maintain control from the core region in the fertile lowlands around London. When British governments overcome domestic divisions, they can turn their attention outward. Control over the surrounding seas was vital for dominance of the Mediterranean and Atlantic Ocean, and from there, the development of the British Empire. Substantial coal and iron deposits along with an intricate river and canal system were among the factors that drove the country to lead the Industrial Revolution in the 1800s. The dominance of the Royal Navy gave Britain control of the oceans and global trade. The United Kingdom's detachment from continental Europe offers protection since a united European empire could challenge the country's independence. Having a voice in the European Union and strong military and economic ties with the United States help London counter this potential threat.