The Steamboat ZS2 Sling carries like a fully supported backpack leaving your line-of-sight and range-of-motion free upfront. Perfect for spey or switch fisherman. A thumb loop allow for easy "slinging" from back to front for quick access to essentials. A large main compartment easily holds a light rain jacket, lunch and boat box, while a secondary face pocket is great for accessory organization and smaller boxes storage.
This slingpack is extremely versatile - the main reason I love it. You can stuff lunch + a light down jacket in the back main compartment (although it might be pretty tight), while also having all the essential tactical gear still accessible. The add-on bottle holder is a huge plus. The only drawback is 'slinging it' over the shoulder each time you need to access the pockets. The buckles + adjustable straps can get caught on your waders + clothing.
Comfortable pack with great design. Enough room for gear and some lunch. Not to mention all the great attachments. Personal favorite attachment is the water bottle holder
I recently bought my first sling pack and, after a thorough review of the available offerings, chose the Umpqua Steamboat ZS2 1200 Sling Pack. I love it so far - the external features are perfectly suited to what I like to carry on the water, it's comfortable across a long day on your feet, has great capacity, has a built-in net holder, and is really well designed. I like how nicely it slips under your arm, in front of your chest, and serves as its own little table when you're re-rigging. Highly recommend this product.