This deal from Amazon for Cyber Mondayis going fast. Get the Teton Sports TrailRunner 2.0 hydration backpack with bladder for only $25.33, with a regular price of $44.79. Since you've just made it over the minimum for free shipping, you'll get that too.
The first time I saw one of these was a friend who rides his bike a lot. He biked over to a party we were having wearing it and I was so intrigued. While I am by far not an athlete, I could definitely see the function for those who do not want to carry water in their arms or on their waist while going on long runs or rides.
The one for sale here during this Lightning deal is the black. The blue and yellow are sold out and the red is $30.
Not just your water, this hydration backpack can carry your phone, wallet, snacks and more. The back panel is also very breathable, as you don't want something heavy and tight on your back on a hot day that is going to cause you to sweat even more.
The loops and shoulder straps adjust so that you don't have to readjust during your hikes. The main pocket is also very easy to access, but positioned so it keeps out the dirt.
I shopped around and found that there weren't any hydration packs for less than $40 and just the bladders alone were $25-$25. This is a straight-up deal.
Here is what one reviewer, out of the many who rated it highly, had to say:
The bags are compact and the material feels of good quality. Perfect for day hikes. Doesn't hold much in terms of cargo but if you need a water pack and enough space to hold snacks and a map and compass, this pack is perfect. Built in whistle on one of the straps was a nice touch too! Would recommend to the day hiker!
This deal ends today, but it is already 30% sold and going up as I type, so don't wait and research elsewhere or it will sell out.
(Expiry: 30th November 2014)