The Little Sub That Still Can

The human-occupied submersible Alvin surfaces from a mission to the seafloor in a photo taken circa 1967—three years after the sub was first built. Two crewmen known as “swimmers” assist in the sub’s recovery, as other crew members watch from Lulu, Alvin‘s first tender ship. Since those early years, Alvin has been upgraded many times, taking on different appearances as new components and engineering designs are added. Alvin got a major upgrade in 2014, adding a new titanium personnel sphere. Additional upcoming improvements will complete the requirements for Alvin to increase its diving capacity from 4,500 to 6,500 meters—deep enough to provide access to 98 percent of the seafloor. (Photo courtesy of Woods Hole Oceanographic Institution Archives)