In polar exploration, a depot is a cache of food, water, and fuel which is left along the planned route at regular intervals while outward bound. On the way back, these caches supply the necessities of life
The reason that depots exist is because it is impossible for a land-based polar expedition to carry all that is needed to survive the entire way to the pole and back. In the deep Arctic and Antarctic, food and fuel cannot be scrounged from the environment. Everything the expedition needs must be carried in, but even a moderate expedition cannot carry all its needs more than a short distance. The more it tries to carry, the shorter the distance all those supplies can be carried.
To solve this problem, polar explorers took a tip from mountain climbers, who had long been using a series of camps in a similar way. By setting up a base camp and several higher altitude camps, a mountaineer could make a dash for the summit and then return to a very high camp, rather than having to lug all his supplies all the way from the base camp and back in a single step.
In the same way, polar depots are laid in a series, with the largest one closest to the point of origin and the smallest one just about a half day’s travel from the desired destination. The division of equipment and supplies is planned out ahead of time, so that it can be dropped off in preplanned depots of a preplanned size and picked up again on the way back. For very long land-based explorations during the great age of polar exploration, the first depot and sometimes the second and third would be laid the year before the exploration.
The first depot, sometimes called the 1-ton depot, always takes the longest to set up, because it holds the most equipment and supplies. It is critical to lay it as far polewards as realistically possible. Thereafter, the intervals between depots should not be too far apart, in most cases no more than 2-3 times the average distance which the expedition can expect to make in a single day. For safety, each depot should hold at least twice the amount of supplies expected to be needed to cover the next stretch.
A single miscalculation of this average distance and needed supplies can be fatal. Robert Scott made 2 critical miscalculations. First, he did not lay in enough extra fuel oil to allow for its evaporation. When he reached his third and second depots, he found much less oil than he had expected. The lack of nighttime heat aggravated the existing frostbite and malnutrition, which reduced the daily distance Scott’s expedition could cover.
The first miscalculation might have been overcome, if not for the second. On his way back, Robert Scott found himself stranded by a blizzard only 11 miles from his 1-ton depot. When he had originally laid it the year before, a combination of poor planning and a blizzard had forced him to lay in the depot 30 miles farther away from the pole than planned. It eventually cost him his life.
Depots are still used today during overland polar expeditions. However, modern depots are usually laid by air support in advance of the ground team. Instead of meat for the dogs, these modern depots often include fresh batteries and gasoline for the snowmobiles.
