In May 2009, Smith was aboard Aquarius to train U.S. Navy divers in saturation diving and prepare for upcoming scientific studies in the Conch Reef area. On May 5, 2009, Smith was assisting two Navy divers, Bill Dodd and Corey Seymour, who were 300 feet from Aquarius using an underwater jackhammer to install a way station that would contain breathable air. Smith informed Dodd and Seymour that he was returning to Aquarius but would be back. Five or ten minutes later, Seymour noticed that Smith was lying on his side in the water, his mouthpiece out of his mouth. Seymour began carrying Smith back to Aquarius, but his air umbilical became fouled about thirty yards from the habitat. Dodd carried Smith the rest of the distance to Aquarius, where the other divers in the habitat helped them get Smith inside. Resuscitation attempts by Dodd, Seymour, and two Navy physicians who dove to the habitat were unsuccessful. Smith was pronounced dead at 3:25 pm by a Navy doctor. His death was the first associated with the Aquarius program. A subsequent investigation by a panel of outside experts determined that Smith's death was caused by a combination of three factors: the failure of the electronic functions of his Inspiration closed circuit rebreather due to hydrodynamic forces from the hydraulic impact hammer being used nearby, Smith's inattention to his handset and head up displays, and the other two divers allowing Smith to return to Aquarius alone. The investigation concluded that due to these issues Smith became unconscious from hypoxia and drowned when the mouthpiece came out of his mouth. Saturation and CCR diving at Aquarius were suspended in the wake of Smith's death, but the review board recommended that they be resumed with the implementation of additional safety measures.
Tributes
Chairman Brian Baird recognized Smith's service on the floor of the U.S. House of Representatives. U.S. Representative Ileana Ros-Lehtinen, whose district includes the Florida Keys and who had met Smith during a visit to the Aquarius facility, also offered a statement of condolence. On May 15, 2009, at a panel at International Space Medicine Summit III devoted to human performance in analog environments, astronaut-aquanaut Dafydd Williams, who had participated in two NEEMO missions, asked for a moment of silence in Smith's memory. Aquarius donated a Superlite 17 diving helmet, the helmet most frequently worn by Aquarius aquanauts, to the History of Diving Museum in Islamorada, Florida in memory of Smith.
Personal life
Smith was a triathlete. He enjoyed playing the drums, tennis, exercising and movies. He was survived by his parents, stepfather, sister, brother, and uncle, among others.