Maloney was an accomplished mountaineer who at the time of his death was believed to be the oldest American ever to summit an Eight-thousander, one of the fourteen peaks in the world that are greater than 8,000 meters in altitude. He climbed five of the Seven Summits, the tallest mountains on each of the seven continents, including Denali in Alaska, Mount Kilimanjaro in Africa, the Vinson Massif in Antarctica, Aconcagua in the Andes, and Mount Elbrus in the Caucasus. On September 24, 2009, at the age of 71, Maloney summited the nearly 27,000-foot peak of Cho Oyu, the world's sixth-highest mountain, in Tibet. He reached the summit of the Turquoise Goddess, as the mountain is known, with the help of a sherpa and a guide, Marty Schmidt. He then descended to Camp 2 at 23,000 feet. On the morning of September 25, 2009 he woke up and told a companion, I'm the happiest man in the world. I've just summited a beautiful mountain. These were apparently his last words as he went back to sleep and never woke up.