From December 1872 to May 1876, Challenger sailed almost 115,000 km (69,000 miles) entering all oceans but the Arctic. A standard set of data was collected at each of 360 stations along their route. Samples and data were carefully returned to Scotland for systematic analysis and documentation.

The three basic techniques available for their scientific study were sounding, dredging, and temperature readings. They also took water samples using various sampling bottles and had a Hydrometer on board to measure the salinity of the seawater by analyzing its density.

The standard set of obserations made and samples taken at each of the 360 stations were:

• water depth


• temperature at various depths


• weather conditions


• water conditions at surface and sometimes at depth


• seafloor samples


• water samples


• samples of plant and animal life
  at various depths

While the Challenger voyage's primary mission was the study of the oceans, many of the islands on their route had not been explored by Europeans, so the scientific crew brought back samples of the plants and animals they found there. The information they recorded about thenative peoples turned out to be very valuable, because these island cultures swiftly changed in later years.