First expedition Marvin took part in the Peary expedition of 1905–1906, shortly after graduating from Cornell. Marvin was very eager to join the expedition, because he felt that it was his life's work. While failing to reach the
North Pole, Peary asserted to have traveled father north than anyone. Marvin committed to accompany Peary on his next expedition. After his return, Marvin became engaged, with plans to marry after his second expedition with Peary. Starting in January 1907, Marvin taught mathematics at
Mercersburg Academy in Pennsylvania, and in September 1907 he joined the faculty at Cornell University as an instructor in mathematics and astronomy. He took a leave of absence from this post in order to participate in Peary's 1908–1909 expedition.
Second expedition Marvin was given the role of chief scientist and keeper of the ship's log. He would record the day-to-day activities of the men, and of the general conditions that the men had to face while headed toward the arctic, which included the weather. Marvin kept a journal of his days on the ice, however the entries began to dwindle as the expedition went on. His last journal entry was on December 8, 1908. However, Kudlookto stated in 1926 that he had shot and killed Marvin, either because Marvin had started acting irrationally, ==Legacy==