Larsen was born in Sandar, and became a noted whaler, captaining a number of whaling ships principally for Thor Dahl A/S of Sandefjord. He also served as a first mate on Norvegia expeditions of Antarctica financed by Norwegian whale-ship owner Lars Christensen. During these expeditions, Norway achieved annexation of Bouvet Island (1927) and Peter I Island (1929).
Larsen died in Sandefjord, at the age of 76. Geographical areas in Antarctica named after him include: Mount Nils Larsen (Queen Maud Land), Mount Nils (Enderby Land) and Nils Larsen Glacier (Peter I Island).
- "Nils Larsen - 2". Norsk biografisk leksikon (in Norwegian). Retrieved 28 March 2017.
- Norman Middlemiss (14 March 2017). "Thor Dahl of Sandefjord". Shipping Today and Yesterday. Retrieved 1 June 2017.
- "Lars Christensen". Norsk Polarhistorie. Retrieved 1 June 2017.
- "Norvegia ekspedisjon". Norsk Polarhistorie. Retrieved 1 June 2017.