Vice-Admiral Sir George Strong Nares (24 April 1831 15 January 1915) was a Royal Navy officer and Arctic explorer. He commanded the Challenger Expedition, and the British Arctic Expedition. He was highly thought of as a leader and scientific explorer. In later life he worked for the Board of Trade and as Acting Conservator of the River Mersey.

The Challenger expedition of 1872–1876 was a scientific program that made many discoveries to lay the foundation of oceanography. The expedition was named after the naval vessel that undertook the trip, HMS Challenger.

Prompted by Charles Wyville Thomson—of the University of Edinburgh and Merchiston Castle School—the Royal Society of London obtained the use of Challenger from the Royal Navy and in 1872 modified the ship for scientific tasks, equipping it with separate laboratories for natural history and chemistry. The expedition, led by Captain George Nares, sailed from Portsmouth, England, on 21 December 1872. Other naval officers included Commander John Maclear.Under the scientific supervision of Thomson himself, the ship travelled nearly 70,000 nautical miles (130,000 km; 81,000 mi) surveying and exploring. The result was the Report Of The Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873–76 which, among many other discoveries, catalogued over 4,000 previously unknown species. John Murray, who supervised the publication, described the report as "the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries". Challenger sailed close to Antarctica, but not within sight of it.