Númenor was surrounded by the Great Sea of Arda, and the sea had a profound influence on Númenor's culture and history. From the earliest times in its history, fish from the sea were a significant part of Númenórean diet; those providing this food were Númenor's first sea-farers. The Númenóreans swiftly became skilled shipbuilders and mariners, with a desire to explore and master the ocean. There was one limitation on this activity: the Ban of the Valar. When the island of Númenor had been gifted to the Edain, they were strictly prohibited from sailing west out of sight of the island. This was because the Undying Lands, forbidden to mortals, lay tantalizingly close to the west of Númenor.