Since the sea mink has only been described by fragmentary remains, its appearance and behaviors are not well-documented. Its relatives, as well as descriptions by fur traders and Native Americans, give a general idea of this animal's appearance and its ecological roles. Accounts from Native Americans in the New England/Atlantic Canadian regions reported that the sea mink had a fatter body than the American mink. The sea mink produced a distinctive fishy odor, and had fur that was said to be coarser and redder than that of the American mink. It is thought that naturalist Joseph Banks encountered this animal in 1776 in the Strait of Belle Isle, and he described it as being slightly larger than a fox, having long legs, and a tail that was long and tapered toward the end, similar to a greyhound.