If you're into long-distance running or training for a marathon it's imperative to stay hydrated. Carrying around a huge water bottle can be annoying though, and most hydration waistpacks only hold 20 ounces of water or less.
Check out this Nathan Speed 4 Nutrition Speedbelt ($34.95). It's a long name for a holder that you wear around your waist that houses four, 10-ounce bottles. That means you get 40 ounces of water total, and because the bottles are spread out, you won't feel uneven pressure or strain on your back or hips. The bottles can also be filled up with special electrolyte drinks or carb gels, since long-distance runners need extra calories in order to keep running. I love that you can easily pull the bottles out with no problem, and they're curved so they fit in one hand comfortably. There's also a little pocket in the front for small essentials. The waistbelt is adjustable so you can get a snug fit without it bopping up and down as you run. Order it from teamestrogen.com.