Iceberg

Mass of glacier-derived freshwater ice protruding more than five metres above sea level. The International Ice Patrol classifies icebergs as growler, bergy bit, small (5–15 m above water, up to 60 m long), medium, large, or very large. Roughly seven-eighths of the mass sits below water, and underwater rams can extend horizontally well beyond the visible profile — the navigational reason vessels keep at least one nautical mile clearance from any sighted iceberg in the North Atlantic shipping lanes during the IIP season.