1875 – HMS Challenger – In 1875, during her transit from the Admiralty Islands to Yokohama, the three-masted sailing corvette HMS Challenger attempted to make landfall at Guam, but was set to the west by "baffling winds" preventing them from "visiting either the Carolines or the Ladrones."[15] Their altered path took them over the undersea canyon which later became known as the Challenger Deep. One of their samples was taken within fifteen miles of the deepest spot in all of Earth's oceans. On 23 March 1875, at sample station number #225, HMS Challenger recorded the bottom at 4,475 fathoms (26,850 ft; 8,184 m) deep, (the deepest sounding of her three-plus-year eastward circumnavigation of the Earth) at 11°24′N 143°16′E﻿ / ﻿11.400°N 143.267°E﻿ / 11.400; 143.267 – and confirmed it with a second sounding at the same location.[2] Depth soundings were by Baillie-weighted marked rope, and geographical locations were determined by celestial navigation (to an estimated accuracy of two nautical miles).