German Icebreaker Polarstern 1 (IMAGE) Census of Marine Life Caption The Polarstern can break through ice 1.5 meters thick at a speed of approximately 5 knots. Credit Alfred Wegener Institute for Marine and Polar Research. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.