This idea comes from American oceanographer Henry Stommel, who in the late 1970s imagined an autonomous equipment to measure the oceans. Until then, it was pretty difficult to get information about the depth, you needed to get on a boat and it was expensive, with many people involved and a complex logistics. He wrote a kind of futuristic short story about this equipment, I think it was in 1989, and the story unfolds during the 20 following years. It stages a race between institutions from different countries, doing a competition of gliders to measure the ocean, and there he described its basic concept. Progressively, researchers have started to work on a prototype looking like what he imagined.