In December, Donald Cash quit his job as a software salesman to finish his goal of climbing the tallest mountain on each of the seven continents. He died Wednesday, just after scaling Mount Everest, the last mountain on his list, his family said.

Mr. Cash, 54, of Sandy, Utah, fainted after reaching the summit and could not be revived. Mr. Cash’s daughter Brandalin Cash and his son Tanner Cash said they believed he had a heart attack.

Situated in the Himalayas, Mount Everest is the highest mountain in the world at 29,029 feet.

Mr. Cash initially fainted at the summit because of high altitude sickness and was helped by Sherpa guides, according to Pioneer Adventures, a company that leads trips on Everest. While en route to a camp near Hillary Step, Mr. Cash fainted once more and his attending Sherpa guides were unable to revive him.