Seatbelts...
If there is a chance of the aircraft rolling over, undoing your seatbelt prior to entering the water is not advisable. When the aircraft rolls inverted or part thereof, being strapped into your seat provides you with a great orientation/reference point in which to find the appropriate exit point (The window/door that was on your right will still be on your right while upside down) As a HUET instructor so many people try to get out the 'other side' when put upside down, so my advice is not to undo the seatbelt/harness.
