From Swallow floats to Argo—the development of neutrally buoyant floats

Neutrally buoyant floats have been a vital tool in the exploration of the global ocean circulation and now provide a central element of the in situ ocean observing system through the Argo project. The paper traces the development of neutrally buoyant floats from their origins in the mid-1950s to the present day, and highlights areas of ocean science to which floats made significant contributions.