The Sea to Summit Hydraulic measures 13-inches wide x 8-inches deep x 28-inches tall. This 35-liter pack is made out of 600D TPU laminated nylon and sports a removable backpack harness with padded shoulder straps and a nylon waist belt. It also features four welded nylon lash patches for easy attachment to your craft of choice.
This model features a comfortable removable backpack harness.
While overall, this product did well, this metric is where it failed to shine. Our gear stayed dry with casual use and when exposed to splashes. Upon submerging it, a fair amount of bubbles escaped, but only a few drops of water entered the main compartment. Unfortunately, when put to the rigorous task of being dragged behind a paddle board through a lake, it on-boarded a significant amount of water, and our testing towel was soaked.
Some large bubbles escaped during our submersion testing.
This product may serve well for casual river days or to store gear that you would rather stay dry, but it won't be a total deal breaker if some moisture gets in. If you're worried about your raft getting flipped and your bag getting dragged through the white water, the Watershed Colorado Duffel offers significantly better protection. If you're devoted to a backpack hybrid model, the SealLine Black Canyon Boundary Pack has a similar design but is significantly more waterproof.
Our testing towel ended up pretty soggy after submersion.
Ease of Use
The Hydraulic has a long and narrow design with a single opening at the top. This means packing from the bottom up and stacking your contents. It's also difficult to reach to the bottom of the pack.
This model was the most comfortable to carry. A handle at the top of the backpack makes a nice handhold when the pack is off your shoulders. The backpack straps are also well padded and adjustable. Unfortunately, the 35-liter model has a webbing waist belt that is a bit painful on your hips with heavy loads.
This handle made it really easy to pick up the bag and we found this feature surprisingly useful.
Padded Waist Belt
This model also comes in 65-liter, 90-liter, and 120-liter sizes. Each of these larger models features a padded adjustable waist belt more like that of a typical backpacking pack.
The Hydraulic scored well in this metric due to its comfortable backpack frame that is quick and easy to remove and reattach. Fully-adjustable shoulder straps make for a more custom fit, and anodized aluminum buckles provide durability. While these buckles are convenient to slip on and off, they are also prone to popping off mid-use. This doesn't greatly compromise the functionality of the product, but it is a bit annoying.
The SealLine Black Canyon Boundary is a similar backpack style product, but it offers no means to secure it to your watercraft. The Hydraulic serves well in this with its four welded TPU lash patches (2 on each side).
The ridged lip helps provide a tighter seal than many of the other competitors.
The roll top closure system of the Hydraulic is unique with an interlaced lip. Grooves in the reinforced lip line up and are intended to create a better seal. While it does allow the bag to withstand brief submersion, it lacks the complete protection of a truly interlocking lip like the one in the Watershed Colorado Duffel.
This model was one of the top scorers in this metric. It is made of a thick and super durable material that can withstand a serious beating. The lash points are also made out of a TPU material and welded into place. Even the backpack attachment points are made of sturdy aluminum.
The backpack straps are held on by metal clips that quick to pop off.
The YETI Panga was the only model to beat the Hydraulic in durability and is our preferred product for traveling. For a backpacking-focused adventure, the Sea to Summit eVent Compression will keep your sleeping bag dry when stashed inside a more ergonomic proper backpacking pack.
The Hydraulic offers versatility for a variety of water-oriented adventures. The backpack harness makes it easy to carry, and the lash points make it easy to attach to your raft. Its best suited for river trips with a majority of time spent in the water but with occasional excursions onto land where a backpack is needed.
At $149.95, this model is one of the pricier products in this review. With this price, however, comes equally high durability and versatility. For canyoneering and caving where you know your bag will spend a lot of time in the water, the SealLine Black Canyon Boundary is quite a bit cheaper. For a similar price, but higher scores across the board, the Watershed Colorado Duffel is a better all-around model.
From paddle board to canyon trip, this bag is durable and easy to use.
The Sea to Summit Hydraulic is a versatile hybrid of a dry bag and a backpack. For river trips that also require the occasional use as a backpack, it's a good product. For more serious backpacking, stick to a traditional backpacking pack.