Remains of toad sculpins and ocean pout were the most common around their dens, and garden banded snails were also reported to have been part of their diet.[2] Their seafood-oriented diet may have increased their size.[3] According to fur traders, the sea mink was nocturnal and resided in caves and rock crevices during the day.[4] Due to the overlap of American mink and sea mink ranges, it is possible that they hybridized with each other.