In early March, a gleaming white submarine called Alvin surfaced off the Atlantic coast of North Carolina after spending the afternoon thousands of feet below the surface. For Bruce Strickrott, Alvin’s chief pilot and the leader of the expedition, these sorts of missions to the bottom of the world are a regular part of life. By the time Alvin’s makeover is wrapped up in late 2021, the storied submarine will rank among the most capable human-rated deep sea submersibles in the world. Courtesy of Woods Hole Oceanographic InstitutionTo upgrade Alvin, engineers had to tear the sub down to its metal skeleton at the National Deep Submergence Facility, a federally funded research space hosted at Woods Hole. The vessel is made almost entirely from custom components designed to withstand the uniquely hostile environment in the deep ocean, and the regular teardowns ensure that everything is in good shape.