Anyway, if your a whitewater paddler you will know that whitewater kayaks have drain plugs to help get the water out after you take a swim. Its a big fear of kayakers that you will loose your drain plug and not be able to fill the hole - particularly when different makes of kayak have different types of drain plugs.
This can be a particular problem on overseas or remote trip when you are unable to get to a shop to get your hands on a replacement.
This is a nice simple idea from Harry Thaler with his Stopp.it drain bung replacement. Simply, change your drain bung fitting once and afterwards you can use any PET plastic bottle top (found all over the world) to keep water out of your kayak.
Simple but effective...