On land off an ice covered sea the traveler can, for example, detect the presence of open water, simply because it reflects less light than land or ice. The open sea's telltale sign is thus a darkness on the underside of the clouds.

I do not believe there is any such sixth sense. A man with a good sense of direction is, to me, quite simply an able pathfinder - a natural navigator - somebody who can find his way by the use of the five senses (sight, hearing, taste, smell and touch - the senses he was born with) developed by the blessing of experience and the use of intelligence. All that pathfinder needs is his senses and knowledge of how to interpret nature's signs.

On land off an ice covered sea the traveler can, for example, detect the presence of open water, simply because it reflects less light than land or ice. The open sea's telltale sign is thus a darkness on the underside of the clouds.