Needs to be done on the Quacking The Ice level.
Wait for the Propeller-hat Ducky to escape the pool. Press "E" until you are in binocular view. You might need to use the scrollwheel to get closer for the Achievement to unlock.
If you are in binocular view while the Ducky is escaping, the Achievement might not unlock until you re-enter it again. You might need to press "E" a few times and/or use the scrollwheel to zoom in a little.