New York representative Carolyn Maloney‘s husband, Clifton Maloney, 71, died in his sleep shortly after a successful summit of Cho Oyu over the weekend. The millionaire investment banker, who has been described as an “avid adventurer” into not only mountaineering but sailing and running (he competed in 20 New York marathons), became the oldest person to reach the top of Cho Oyu.

After the summit, Maloney’s team descended to one of their prepared high camps to rest after a long day at altitude. Reportedly he told one of the other climbers: “I am the happiest man in the world. I just climbed a beautiful mountain.” He then crawled into his sleeping bag for the night, and never awoke. Maloney is survived by several women–his wife, mother, sister, and two daughters.

Cho Oyu, perched a dozen miles west of Mount Everest and often considered the softest of the world’s 14 8,000-meter peaks to climb, is the sixth tallest in the world at 26,906 feet. Maloney’s family is working to get Clifton’s body down the mountain; due to his age and the extreme altitude, he most likely suffered from cardiac arrest or respiratory failure. According to this table, Maloney will be considered the 42nd person to ever die on Cho Oyu.