When flying over water or land you need to think about and be prepared incase something goes wrong. Dressing properly in case you happen to be unlucky and have to force land in the mountains. It may take some time for the SAR guys to get to you. You need to know what to do and what not to do. There was an article in pilot recently about a single that had a problem in the mountains it is definately worth a read. . .Likewise if you are flying over water ie to France if you have the luxury of being able to get hold of an immersion suit then use it. It may look silly waddling around, but the Channel is cold and your survival time is very low without one. I have done survival courses and the facts speak for themselves. This is one area you don't want to leave to chance. A little effort and thought could save your life or those of your pax.