1923-

English physical oceanographer and geophysicist who discovered the countercurrent to the Gulf Stream during the International Geophysical Year (1957-58). After conducting extensive seismic refraction experiments and data collection, Swallow joined the British National Institute of Oceanography, where he developed his neutral buoyancy float in 1956. Sinking to a predetermined depth, the float could drift and be acoustically tracked. Swallow's float revealed the Gulf Stream countercurrent, strong mesoscale eddies at all depths in mid-ocean, the Somali current, and equatorial circulation in the Indian Ocean.