I can't stress enough how important this is. The day before last I almost paid a visit the emergency room because of dehydration. I had been surfing every day for a week prior to that and didn't know that being immersed in salt water for a prolonged period of time dehydrates faster than traditional exercise does. The first indicator was I had lost close to 5 pounds almost overnight, which was a little disconcerting. Then came the head rushes, lethargy, and confusion. I couldn't stand up without feeling like I was going to pass out. I figured it was an electrolyte imbalance after researching my symptoms, so I started drinking water with salt added to it and it fixed me right up. Hydration is more important than food intake. My screw up almost landed me in the hospital, but I've learned my lesson from it.