Sea of the West

The Sea of the West, or Mer de l'Ouest, was a geographic misconception of an inland sea in the Pacific Northwest that appeared on many maps of the 18th century. The depiction was particularly common on French maps. The sea was supposed to be connected to the Pacific Ocean by at least one strait. Many different conjectures about the sea's shape, size, and position appeared on maps of the period.

Belief in the sea's existence derived from writings describing two voyages of discovery, one by an Admiral Bartholomew de Fonte, and one by Juan de Fuca. De Fuca's voyage might have happened, but his account is now known to have contained many distortions and confabulations. Admiral de Fonte, on the other hand, is not known to be a historical figure, and the account of his voyage is fiction. Several maps in the early 1700s depicted the sea, but interest and belief in its existence waned until the mid 1700s, when, fairly suddenly, Mer de l'Ouest reappeared on maps and quickly became common for several decades.

European knowledge of the region gradually improved such that belief in the inland sea became untenable before 1800.