or MAGALHEANS, STRAIT OF, an arm of the sea which separates Patagonia from the group of islands lying to the S. of South America, of which the principal is Tierra del Fuego. It received its name from Ferdinand Magellan, who first sailed through it from the Atlantic to the Pacific. For some time after this it was thought to be the only communication between the two oceans; but since Cape Horn has been doubled, it is little used on account of the difficulty of navigation. The entrance to the channel at the eastern end is situate in about S. Lat. 52°, and is 15 miles in breadth, while that on the side of the Pacific extends to 33 miles. There is, however, another arm reaching to the Pacific by Cockburn Channel and Magdalen Sound. The breadth of the main strait varies very considerably, being at one point not more than 13 miles across. The middle of the strait is much farther S. than either of its extremities, and the whole length is nearly 300 miles. It is bounded by precipitous rocks, rising in some places to 3000 or 4000 feet above the level of the sea, and the depth in some places is so great as to give no soundings with a line of 1500 feet. Towards the western mouth the strait is broken up by a number of islands.