I just saw Bob Pauli's helpful reminder--via Grandpa Spey--to hydrate, and wanted to mention something that you may or may not know: that drinking too much plain water is as dangerous, if not more dangerous, than drinking too little. Drinking lots of water on a hot day can deplete your electrolyes in a matter of hours, and that can lead to heart failure or stroke. I used to fish the Deschutes like a madman in June and July, and noticed that I was getting serious headaches after a long day of fishing. Not enough water, I thought. So I drank more. Headaches got worse and exhaustion increased: it would take a day or two to recover from a day of fishing. Finally called the doctor and described my symptoms, and she recognized it immediately as electrolyte depletion, which can be fatal, especially when you try to ease your symptoms by drinking more water. So, when you hydrate on those hot days, drink a sports beverage of some sort, and replace your electrolytes along with your precious bodily fluids.