Explorer, who was the first man to walk across the frozen Arctic Ocean, and some say the first man to reach the North Pole on foot. He and his four-man team completed the 3,620-mile trek on May 30, 1969. He brought back 250 ice-core samples from that 16-month expedition, which help scientists measure the impact of climate change in the arctic. He learned surveyor skills in the 1950s and 60s as a member of the Royal Engineers in the Middle East and British Antarctic Survey. He mapped thousands of miles in the Arctic and Antarctic. According to the Royal Geographical Society, an Antarctic mountain range and an Arctic mountain are named after him. Sir Wally died due to diabetes complications.