There are many convincing situations could be found in water sports, e.g. scuba diving, surfing, windsurfing, etc. I have been in a real survival situation when my windsurfing board broke in the storm and after 5 hours of struggling I've managed to land on an unknown shore of the wide river. I was exhausted and cold to death, but miraculously run into a local fisherman who made a big warming fire for me. I'm more into scuba diving now, but always taking my peanut lighter on the pictured above necklace under the wet suit. Unfortunately it's flooded last time after the 90' dive, but I think I can work on that problem.

Another reason - ease of concealment from a typical body search.