In the 1500 metres at the 1908 Summer Olympics, Dahl placed seventh in his initial semifinal heat and did not advance to the final. At the 1912 Summer Olympics he participated in the individual cross country competition, but did not finish. As such, he did not place in the team cross country competition. He became Norwegian champion in 1500 metres in the years 1906-1909 and in the 5000 metres in 1908.