We may commence by saying that no such voyage has in truth ever been undertaken before.(25) Nearly 70,000 miles of the earth’s watery surface were traversed, and the Atlantic and Pacific crossed and recrossed several times. It was a veritable _voyage en zigzag_. Apart from ordinary soundings innumerable, 374 deep-sea soundings, when the progress of the vessel had to be stopped, and which occupied an hour or two apiece, were made, and at least two-thirds as many successful dredgings and trawlings. The greatest depth of ocean reached was 4,575 fathoms (27,450 feet), or _over five miles_. This was in the Pacific, about 1,400 miles S.E. of Japan. We all know that this ocean derives its name from its generally calmer weather and less tempestuous seas; and the researches of the officers of the _Challenger_, and of the United States vessel _Tuscarora_, show that the bottom slopes to its greatest depths very evenly and gradually, little broken by submarine mountain ranges, except off volcanic islands and coasts like those of the Hawaiian (Sandwich) Islands. Off the latter there are mountains in the sea ranging to as high as 12,000 feet. The general evenness of the bottom helps to account for the long, sweeping waves of the Pacific, so distinguishable from the short, cut-up, and “choppy” waves of the Atlantic. In the Atlantic, on the voyage of the _Challenger_ from Teneriffe to St. Thomas, a pretty level bottom off the African coast gradually deepened till it reached 3,125 fathoms (over three and a half miles), at about one-third of the way across to the West Indies. If the Alps, Mont Blanc and all, were submerged at this spot, there would still be more than half a mile of water above them! Five hundred miles further west there is a comparatively shallow part—two miles or so deep—which afterwards deepens to three miles, and continues at the same depth nearly as far as the West Indies. [Illustration: EXAMINING A “HAUL” ON BOARD THE “CHALLENGER.”]