Sea To Summit Big River 50L Waterproof Backpack Review

Last Updated on 05/03/2024


In this review of the Sea To Summit Big River 50L Waterproof Backpack, I share the results of testing this backpack over the past few months. You will learn what I think works very well, what you shouldn’t expect from this pack, and why I think it’s worth the money.

I have been wanting another fully waterproof backpack since my last one (an 18-litre waterproof backpack from Alpkit) got a big split in it. I used to use it for hiking in heavy rain and cycling to work. That’s why I was so excited to get my hands on this large dry bag backpack.

Sea To Summit Big River 50 L Waterproof Backpack Review


Are you in a hurry? Here is the bite-size review of the Sea to Summit Big River Backpack.

This minimalist waterproof backpack is the best for carrying larger items you need to keep dry. You can’t overload it because there’s no frame, and there are no organizational features beyond the webbing on the outside of the pack. But dang, is this thing lightweight and practical.

The material is durable enough not to worry about ripping easily, and it feels really well made. If you want a backpack to keep things like your clothes, sleeping equipment, and supplies dry, then this is one of your best options. For heavier gear, it wouldn’t be the best for hauling over longer distances due to the lack of a frame, but it is certainly up for the challenge if you want to give it a go.

Its best uses are for watersports like kayaking, sailing, and stand-up paddle boarding, as well as for cycling and motorbike travel. You can use it for hiking, too, but I would only do this again if the weather was bad, I had lots of river crossings, or my gear didn’t weigh very much.

Sea to Summit Big River Dry Backpack with Adjustable Harness, 50 Liter, Picante Red


Sea To Summit Big River Specifications

Here are the specifications of the Sea to Summit Big River waterproof backpack:

  • WEIGHT: 1lb 10 oz / 760 g
  • VOLUME: 50 liters (Imagine a large bag of garden compost)
  • SIZE: 23.9 x 13.6 x 11.2 in / 60.4 x 34.5 x 28.5 cm
  • MATERIAL: 420D Nylon face fabric bonded to TPU lining
  • HH RATING: 10,000mm
  • FRAME: Frameless
  • POCKETS: No pockets, although you can attach things to the outer webbing.

Sea To Summit Big River Features

Here are the features of the Sea to Summit Big River waterproof backpack:

  • Fully Waterproof: Patented buckles seal water out.
  • Padded Straps: Adjustable EVA foam shoulder straps with rigid padding.
  • Harness: Adjustable waist belt
  • Rugged Resilience: 420D Nylon fights wear and tear.
  • Grip & Secure: Versatile daisy chain for confident attachment.
  • Illuminate Inside: White TPU brightens gear view.
  • Eco-Conscious: Always PFC-free.

Sea To Summit Big River Review

First Thoughts

When the bag first arrived, I was surprised to find it had what seemed to be a rigid back (which I wasn’t expecting). It turns out this was just the cardboard packaging inside used to keep its shape. You’ll find out later why keeping turned out to be a good idea. But once I took that out, the first thing I noticed was how light the bag was. For some reason, I was expecting it to be heavier.

The size IS what I was expecting because I have many other backpacks with a 50-litre capacity (but none of them are fully waterproof). It’s big enough to fit a tent, sleeping bag, mat, food, water, tools, bundles of wood, and clothes. However, I don’t think that is what this pack is designed for.

It’s not a hauling backpack you would want to fill with heavy gear or too many pointy things. Instead, it’s a bag where you can keep your essential clothes, food, sleeping bag, and maybe a tent when it’s raining constantly or you are traveling by water. You can strap other items to the webbing on the sides if you need to, but the inside of the pack is best reserved for soft items that you really don’t want to get wet.

Imagine a kayak trip where you might need to portage a kayak on your head. Wouldn’t it be better if you could carry your gear on your back to keep both hands free? Yes is the answer. For a hiking trip where the rain won’t let up for days, keeping your gear 100% dry is a huge benefit.

Who is the Sea to Summit Big River Waterproof Backpack For?

The Sea to Summit Big River Waterproof Backpack is the best lightweight waterproof backpack out there at the moment. It is perfect for all kinds of water activities and paddle sports, as well as biking, motorcycling, and light hiking trips. It is for anyone who wants to keep their gear dry in an easy-to-carry backpack.

Stand-up paddle boarding is a fast-growing sport, and this would be a great bag to carry all your clothes and towels in, as well as something you could use to carry a wetsuit back home without it dripping all over your car. People who commute to work on bicycles could easily fit a laptop, a small portfolio, and spare clothes in this bag. Surfers could leave this on a beach to keep the sand off their gear. I’m sure you have a use for this bag I have never even thought of…

Photographers and researchers carrying expensive equipment could absolutely use this to protect their gear and keep it dry. Fishers and hunters who have to make river crossings with all their gear would also see the benefits of a backpack that is as waterproof as this.

This would be an amazing bag to take backpacking as it rolls up to fit inside your main backpack and is big enough to fit your main backpack inside when you need to keep it dry.

Sea to Summit Big River Dry Backpack with Adjustable Harness, 50 Liter, Picante Red

Size and Weight

The Sea To Summit Big River backpack offers a full 50 liters of usable space, which means you can easily fit a sleeping bag, clothes, food, and a tent. It is big enough for weekend trips where you need everything in one bag, or if you are traveling by kayak or boat, then it has more than enough space for the things you need to keep dry.

At just 760 grams, you would be hard-pushed to find a backpack this big that weighs so little. It’s so lightweight and minimal that you can easily roll it up and keep it inside a more heavy-duty backpack with a frame for those times when you need it – like river crossings and rain storms.

Sea To Summit Big River 50L Waterproof Backpack side view

Hauling Capacity

The Big River Sea To Summit Backpack is not designed for hauling heavy gear; it is for mostly soft goods like sleeping bags, clothes, and other items that would become useless if they get wet. I would suggest that you should try and keep the total weight to around 7-8 kilograms where possible. This is to avoid damaging the bag as well as not make it so uncomfortable to hike or bike with. 

Because there is no frame for support, you are relying on the material to hold all the weight, which doesn’t transfer to your shoulders and hips as effectively. There are hip straps, and the shoulder supports are adjustable. It’s just not as good as a purpose-built backpacking backpack with a strong frame built for hauling.

I tested the Big River Backpack with my full weekend kit or camping gear and supplies, and it fit in there with no problems. This weighed a total of 9 kg, including the bag. I had to pack it strategically so that I couldn’t feel any jagged edges sticking in my back and also to make sure there were no pointy edges that risked puncturing the bag from the inside.

The good thing about carrying gear in a waterproof rolltop backpack like this is that the less stuff inside you have, the more times you can roll the fabric to reduce unused space. It is very adaptive in this way.

Sea To Summit Big River backpack review


Despite not having a frame and having limited adjustability, the backpack itself is very comfortable to wear. It feels a little bit weird when the bag is mostly empty, and when it is perhaps slightly overfilled, it also feels a little high on the back. The sweet spot is when it is filled with lightweight and bulky gear so that there isn’t much dead space inside the bag.

The shoulder straps are very stiff with firm padding, which works well long term and helps them to keep their shape. The waist straps have no padding at all and instead are just 38 mm webbing, which can be removed if wanted. I actually don’t think hip straps need a lot of cushioning, so these are fine for me. They are also removable.

I found that keeping the cardboard insert (that came with the bag) at the back provided just enough protection between my back and my gear to avoid most of the discomfort when carrying solid items like my stove, pans, and accessories. A foam pad or similar insert would probably work better than the cardboard, but as a cheap and simple solution, it works very well.

Sea To Summit Big River 50L Waterproof Backpack durable base


The entire upper backpack is made from an ultra-durable 420D nylon that is abrasion and puncture-resistant. The base is the same but also has three coatings of even more abrasion-resistant material on top. This triple-coated base is what’s needed to avoid damage when you pick up and put down your bag thousands of times over its lifespan.

I haven’t put that many miles on the clock yet, having only been using it for three months so far, but I haven’t shied away from throwing it onto rocky river banks or rugged ground. I would imagine this bag would last at least 5-10 years of heavy use before it needed to be replaced or patched.

The only improvement that could have been made with the durability of the base is if it had some kind of solid plastic nubs on the corners; otherwise, I am more than satisfied it won’t get easily damaged. The oval-shaped bottom helps it stand up better than if it was round, which is another nice touch.


The shoulder straps are fixed in position; however, they are adjustable in length, and they also have load lifters at the top to help shift the weight of your bag to fit your body type. I found that I preferred to wear the shoulder straps a little tighter than I would normally; however, this did mean that the waist strap sat a little high. The waist straps are fully adjustable as well as removable, so you can get a good fit no matter how big or small you are. 

One thing I think often goes unmentioned with a bag like this is that the volume is also adjustable. You can add a couple of extra rolls in the lid to reduce the space or even fasten them down using the side buckles. So, while it isn’t the most adjustable bag in the conventional sense, it does have its advantages and isn’t underequipped by any means.

What the Sea To Summit Big River Dry Backpack Doesn’t Have

Let’s not hide the fact that there is no rigid frame on this bag, nor are there any pockets or even a single zip. That’s OK; that’s not why you’d buy this bag anyway. It’s an extra durable dry sack with shoulder straps and a waist belt with webbing up the sides, not a travel bag optimized for organization and features.

If you want a backpack for hauling heavy gear all day, every day, this isn’t the bag for you. If you want a bag with lots of features and organizational pockets, this bag isn’t for you.

Sea To Summit Big River 50L Waterproof Backpack water droplets

Is the Sea To Summit Big River Dry Backpack Worth It?

The Sea To Summit Big River bag is definitely worth it for certain sports and adventures. There aren’t many waterproof roll-top backpacks of this size and of this quality. But of what is out there, this is the one I would choose. It isn’t overly pricey and is very well made; I love mine.



Thanks for reading this Sea To Summit Big River 50 L Waterproof Backpack Review; let us know your questions below.

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This article has been written and/or edited by Andrew N. 20+ years of hiking, mountaineering, and camping experience, with access to all the latest outdoor gear.

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