Independent tactical navigation through ice requires a wide range of near-real-time information regarding the current ice and sea conditions to assist the crew. The ability to identify ice features that may either hamper (ice ridges, ice rafting, snow on ice) or assist (leads, polynyas) the vessel's ability to traverse the sea ice is of great importance both from a safety and efficiency point of view. Weather and ice drift forecasts are necessary to avoid entrapment within the ice due to unforeseen ice movements.