The fact that all northbound voyages had, sooner or later, been stopped by ice was rationalized through a belief that the undiscovered sea was encircled in a ring or "annulus" of ice which, it was thought, could be penetrated via one of several warm-water gateways or portals.
Den kendsgerning, at alle nordgående rejser før eller senere var blevet standset af is, blev rationaliseret ved en tro på, at det uopdagede hav var omkranset af en ring eller "annulus" af is, som man troede at kunne trænge igennem via en af ​​flere varmtvandsporte eller -portaler.