Mainmast Peak is more notable for its steep rise above local terrain than for its absolute elevation.

The nearest higher neighbor is Mount Butters, 4.83 km (3.00 mi) to the west.

[3] The first ascent of Mainmast's summit was made in 1972 by Andrew J. Kauffman II, Judge David Michael, Arnold Wexler, and John Markel.

[7][8] The landform was named by Andrew J. Kauffman II who imagined the peaks on Schooner Ridge as resembling sails on a four-masted ship.

The mountain's toponym was officially adopted on October 3, 1973, by the Geographical Names Board of Canada.