This Day In History: 1872-12-30

The Challenger Expedition. On this day HMS Challenger carried out the first dredging operation of the voyage, bringing up samples of mud and several species of fish from a depth of 1125 fathoms (2 kilometres) off Vigo, Spain.
The voyage encompassing the world’s great ocean basins and lasting from 1872 to 1876, had the aim of investigating the physical and chemical characteristics of the deep sea along with its biology and was the first expedition to be carried out purely for marine science.