Dave Williams is the first Canadian to have lived and worked in both in outer space and in the ocean.
Dr. Williams left his position as emergency room director at the Sunnybrook Health Science Centre in Toronto when he was one of four successful candidates from a field of 5,330 applicants chosen for astronaut training with the Canadian Space Agency in 1992.
In 1995, he was selected to train as a mission specialist for NASA in Houston, Texas. Just three years later, Dr. Williams spent 16 days in space as part of a Neurolab team aboard the space shuttle Columbia, making him the seventh Canadian in space. During the mission, the seven-person crew served as both experiment subjects and operators for 26 life science experiments dedicated to the advancement of neuroscience research, focusing on the effects of microgravity on the brain and the nervous system. Dr. Williams also functioned as the crew medical officer, the flight engineer during the ascent phase, and was trained to perform contingency spacewalks.
During his second mission, in 2007, Dr. Williams was part of a crew which traveled to the International Space Station. This time, he performed three spacewalks, becoming the second Canadian to perform the operation, and setting a Canadian record for total number of spacewalks.
In 1998, Dr.Williams became the first non-American to hold a senior management position within NASA. In addition to his space assignments, Williams is an accomplished aquanaut, participating in the joint NASA-NOAA (National Oceanic and Atmospheric Administration) NEEMO 1 mission, a training exercise held in Aquarius, the world's only underwater research laboratory.