navigation through ice, usually with the assistance of an icebreaker
navigation through ice, usually with the assistance of an icebreaker
traffic on ice, either on an ice road suitable for ordinary road vehicles, or with vehicles designed for moving on snow
traffic on ice, either on an ice road suitable for ordinary road vehicles, or with vehicles designed for moving on snow
traffic on ice, either on an ice road suitable for ordinary road vehicles, or with vehicles designed for moving on snow