Operation HIGHJUMP, officially titled The United States Navy Antarctic Developments Program, 1946–1947, (also called Task Force 68), was a United States Navy (USN) operation to establish the Antarctic research base Little America IV. The operation was organised by Rear Admiral Richard E. Byrd, Jr., USN (Ret), Officer in Charge, Task Force 68, and led by Rear Admiral Ethan Erik Larson, USN, Commanding Officer, Task Force 68. Operation HIGHJUMP commenced 26 August 1946 and ended in late February 1947. Task Force 68 included 4,700 men, 13 ships, and 33 aircraft.

HIGHJUMP's objectives, according to the U.S. Navy report of the operation, were:

1. Training personnel and testing equipment in frigid conditions;
2. Consolidating and extending the United States' sovereignty over the largest practicable area of the Antarctic continent (publicly denied as a goal before the expedition ended);
3. Determining the feasibility of establishing, maintaining, and utilizing bases in the Antarctic and investigating possible base sites;
4. Developing techniques for establishing, maintaining, and utilizing air bases on ice, with particular attention to later applicability of such techniques to operations in interior Greenland, where conditions are comparable to those in the Antarctic;
5. Amplifying existing stores of knowledge of electromagnetic, geological, geographic, hydrographic, and meteorological propagation conditions in the area;
6. Supplementary objectives of the Nanook expedition (a smaller equivalent conducted off eastern Greenland).