The 46-year-old vessel discovered the hot volcanic vents on the ocean floor that transformed ideas about where and how life could exist, famously located an H-bomb lost at sea and made one of the first surveys of the Titanic, the BBC reported Thursday.
The undersea veteran was withdrawn from service this week to prepare it for a two-phase, $40 million upgrade that will allow it to stay submerged longer and go much deeper than its current 14,800-foot limit.
"Going to 4,500 meters (14,800 feet) means we can dive in about 68 percent of the ocean," said Susan Humphris of the Woods Hole Oceanographic Institution in Massachusetts, which operates the submersible.
"When we go to 6,500 meters (21,000 feet), we will have access to 98 percent of the ocean. That will make a huge difference; there is so much more to see down there," she said.
Alvin made its first dive in 1965 and since then has completed more than 4,500 dives, carrying some 1,400 scientists and researchers to the ocean depths.