The last few years, I've been using my Camelbak for fishing, wading, and kayaking. I love it and consider it essential gear for anything and everything I do outside. The CamelBak has been around for years, but if you're not familiar. It's basically a backpack with a 2 liter reservoir and a 2 foot straw. I strap it to my kayak's seat and wrap the straw around the chair. I can drink while fishing or paddling. It's out of the way but there when I need it. Very convenient.
When I stop to wade, I take it off the seat and wear it. It's got a few pockets if you want to pack snacks or fishing stuff (like your fishing license, sunscreen, phone, etc). My fly line never snags on it and it's not heavy. The biggest advantage is where you carry the water and having ready access to it. You can pound the pads with a baitcaster or keep a fly in the drift while you're hydrating and never look away or put the rod down. Fish more and be more productive, while you avoid dying from heat stroke...AWESOME!
Be really cool to see a kayak manufacturer come up with something similar for their kayak seats. Until that happens, this alternative can help you avoid getting dehydrated while your fishing/kayaking. The water is literally sitting on your shoulder...so fish and drink on! Stay hydrated my friends.
**Other models have lots of pockets, bigger reservoirs, and can carry a lot more gear. I prefer the lighter set-up. I've owned this one for about 10 years and had to replace the reservoir twice. I consider that pretty durable. http://www.camelbak.com/
***Store the reservoir in the freezer to cut down on mold that might grow (can be hard to clean)