Fishpond Blue River Chest/Lumbar pack. One of our most popular packs, for a number of good reasons. The Blue River Chest/Lumbar pack is a great alternative to a vest, with the versatility to be worn as a lumbar, chest or sling pack. Regardless of how you wear it, everything you need on the water is right at your disposal, and out of the way when you don't. You'll be surprised at how much you can carry in the the Blue River pack.