My friend and I regularly go salmon fishing on the local rivers. While wading across the river he accidentally submerge his iphone. Now the screen is dark and the button doesn't work.
On our next outing I decided to carry my phone in a zip-lock bag as a safety precaution. I was pleasantly surprised to find that the touch screen still works while inside. The display can also be easily viewed through the plastic. This no-brainer actually works quite well.
The next time you go near water, try putting your cell phone in a zip-lock bag. It is a cheap way of avoiding a costly mistake.