The submersible Alvin has been operated by the Woods Hole Oceanographic Institute (WHOI) since 1964. The first deep-sea submersible to carry passengers (typically a pilot and two scientists), Alvin has been instrumental in several crucial discoveries, including the Project FAMOUS (French-American Mid-Ocean Undersea Study) confirmation of sea-floor spreading at mid-ocean ridges in 1974 and the first visit to a hydrothermal vent – known as black smokers, due to the dark plume of chemicals they emit into the water – off the Galapagos Islands in 1977. Alvin has been used by scientists to discover hundreds of species of animals, ranging from the stunning red tube worms and albino crabs that populate the vents to the anaerobic bacteria that underpin the vents’ ecosystems. Perhaps most famously, Alvin made a dozen dives to the wreck of R.M.S. Titanic. WHOI continues to modify the sub with upgrades, most recently in 2012.