Since the HMS Challenger sailed from England on a four-year oceanographic voyage around the world in 1872, most coastal nations have maintained fleets of research vessels and laboratories for the study of the sea and its creatures. The Challenger voyage was the first systematic attempt to catalogue the depths, contours, and conditions in the ocean as well as to capture and catalogue the animals that live there. Modern research vessels are equipped with trawls, electronic sounding equipment, sophisticated gear for measuring currents, temperatures, and other sea conditions, laboratories, dark rooms, underwater cameras, SCUBA diving equipment, and even submarines and other underwater vehicles. A research vessel may be as small as a skiff or as big as an ocean liner, depending on its mission.