ABE, a nomadic adventurer that plumbed the world’s oceans on its own, forever changing the way scientists explored the seafloor, was lost at sea March 5 off southern Chile. The autonomous underwater vehicle was about 16 years old and in the off-seasons was stored in Woods Hole, Mass.

ABE had been enlisted after a period of semi-retirement to help researchers look for hydrothermal vents at the Chile Triple Junction, the meeting point of three tectonic plates. It was most likely destroyed by the implosion of a pressure housing or buoyancy sphere under enormous water pressure at a depth of about 10,000 feet, said Dana Yoerger, a senior scientist at Woods Hole Oceanographic Institution and one of the engineers who built ABE in the early 1990s with a $1.1 million development grant.

Dr. Yoerger, speaking from the research vessel Melville, which was using ABE to survey the seafloor, said two acoustic transponders aboard the craft had failed simultaneously. “For both to die at exactly the same time means probably something very bad and very violent happened,” he said. The implosion of one pressure structure would have generated a shock wave that would have destroyed others, rendering the craft inoperable and consigning it to the seabed forever.

With its two bulbous pods attached to a cylindrical main body by V-shaped struts, ABE, short for Autonomous Benthic Explorer, resembled a pillowy Starship Enterprise and was a familiar sight on expeditions by Woods Hole scientists and others. It was one of the earliest autonomous underwater vehicles developed for civilian use, and one of the most successful. Its last dive was the 222nd of its career, which began in 1994.