Khoo climbed Mount Everest in 1998 as a member of Singapore's first Mount Everest expedition. In 1999, he skied to the South Pole as the leader of Singapore first Antarctica expedition, covering a distance of 1,125 km in 57 days. In 2001, he climbed Mount Ararat in Turkey together with six other Everest summitters from Turkey, Colombia, the United States and Mexico as part of a Peace Climb project to raise funds and promote international friendship. In that same year, he climbed Shishapangma in Tibet becoming the first South East Asian to climb an 8,000-metre peak without supplemental oxygen.