I posted this on the General section, but figure kayakers use tons of these boxes so probably more helpful here. Anyway's, I use the Outdoor Products - Watertight Boxes for protecting my battery, cell phone, wallet, etc. I actually use about four on a general basis. Unfortunately, the gasket they use don't tend to last very long and start cracking. Once a crack makes it through, it will leak and you have a box, but no longer water tight. I wanted to see if I could find a solution. After some suggestions from Forum members, I headed to Home Depot and found something that worked perfect. Check out the video if you have some old boxes or current ones on the verge of leaking, and try this fix. $3.28 and you can fix probably 20 boxes.