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REI Mars 80

rated 4.5 of 5 stars
photo: REI Mars 80 expedition pack (70l+)

An REI homerun! Perfect performance/price ratio. REI always comes through. Love their R&D folks and great products (like this!) and support.


  • great weight distribution and adjusments
  • fits a wide range of torso lengths perfectly
  • durable


  • larger and heavier than pricier brands
  • no lumbar ventilation
  • the elastic side pockets could be made of a better material

I am a father, so i frequently carry more than my own full load. i often backpack with my 11-year-old daughter, and i don't want to ruin her experience (or love of backpacking!) by making her carry more than a fifth of her body weight. this is why i have a pack this large.

I have used this pack in yosemite (30 miles per trip of backpacking <35 lbs. because i also carried daughters' food and other items), zion (30 miles per trip of backpacking <25 lbs.), and all over texas (including 25+ miles in guadalupe mountains and 45+ pounds due to having to carry water).

I love this pack. for summer backpacking it is a bit large for one person and anything less than three nights, but i think it nevertheless compresses well and carries both heavy and light loads perfectly. Another REI homerun!

Source: bought it new
Price Paid: applied a 20% discount to full price - $172 with tax in Texas

This pack is for the strong hiker who knows what he wants. If you want to go for a 5-day trip and be ready for everything then you'll need some space. The Mars pack from REI has the space, durability, and features to make a good length trip very enjoyable.


  • Versitility
  • Durability
  • Space


  • Durability leads to heavier pack
  • No rain cover

Fit: Nice and adjustable

Comfort: Classic hiker pack feel. Good shoulder straps.

Capacity: Perfect amount for the longer trip.

Organization: 7 pockets give you options

Ride: Weight goes to hips so well. Just what you need.

Compression: Like all good packs, there are compression straps that hold it all in place once loaded.

Ease of use: For now, no problems at all. Good quality. 

Features: Nothing too flashy, which is good. Classic features hold through.

Construction/Durability: Nylon is the way to go. Good in the backwoods.

Source: bought it new
Price Paid: $140

You can disappear for seven days with this very comfortable pack without leaving any gear behind.


  • Lots of room
  • Rugged construction
  • Comfortable
  • Easily adjustable
  • Easy to get to any part of the pack quickly


  • No rain cover
  • Wish top pocket converted to a fanny pack

Great Pack. I have used this on a 50-mile trip hiking the north loop in Glacier National Park and a 38-mile trip on the AT in North Carolina. I carried six days worth of food on both trips. I tend to bring  a lot of unnecessary gear, chairs, hammock, electronics, and a big first aid kit. The Glacier trip I carried 65 pounds without discomfort and had to scramble a couple of times.

Pack feels like a part of your body. Easy to adjust on the move. I will own this one until it falls apart from old age. No rain cover, but I bought the 100 liter REI pack cover and it fits like it was made for it. The top expands 10 more liters if you need extra space. The side pockets are deep and each one will hold two 1 liter smart water bottles. 

Source: bought it new
Price Paid: $150

Super awesome pack, great for hiking. Don't worry about the weight as the hip straps are awesome. The duffle bag feature is great as well.


  • Plenty of storage
  • Can open like a duffle bag


  • The hydration pack sleeve is a little small
  • Very large, not for hyperlite hiking at all

The REI Mars 80 has multiple sizing options so fit is always taylorable and makes the bag extremely comfortable. This was my first larger pack and I am super happy with it. It has a sleeping bag compartment which is nice.

I just took it on a weekend trip in 80 degree weather and it was still comfortable and didn't heat me up too much. I even wore it shirtless and the mesh was comfortable. There are plenty of different compartments which is nice but not so many that you can never remember where you put everything. There aren't any loops on the outside so if you want to hang things from it this is not the backpack for you.

All in all a great buy. Good price and awesome quality.

Source: bought it new
Price Paid: $200

I purchased this pack for a 4-day 3-night backpacking trip along Pictured Rocks National Lakeshore in early spring. The threat of rain and snow was present in the Upper Peninsula, so I needed a pack which would hold all of my gear (including a 25-year-old The North Face synthetic bag and an original Therm-a-Rest pad) including foul weather gear, tent, clothes, extra clothes, cooking system, and the 10 essentials.

Seeking value in this investment was important to me, as my budget is limited, but I want to invest in long lasting gear.

All that said, I was VERY comfortable with the Mars 80. Not being in prime shape (duh) this pack ensured my comfort during hikes between 6 miles (after 7 hours in a car) and two to eight miles a day on relatively flat trails.

I will continue to update this review as I go winter backpacking, another round at PRNL, and all great areas around America's High Five!

Price Paid: $165

I bought this pack for a Philmont trip in 2011. Have used many times and still going strong. Very durable and holds everything I need.


  • Storage capacity
  • Multiple pockets
  • Easy access from top or through back zipper


  • Separate compartment for sleeping bag/tent

This pack has great flexibility and is easily adjusted while on the trail. Plenty of capacity to really pack in everything you need. Always seems to have more room even when it doesn't seem possible. Love all the easy access pockets.

Source: bought it new
Price Paid: $150

I don't own this pack, but a friend of mine did. I was backpacking with him on the first day of a 5ive-day trip in 2004 in north Yosemite when the shoulder strap broke off from the plastic adjustable suspension plate, while hiking. Brand new pack, it was the first time he'd used it.

He tied the strap back with regular pack straps, but it was an annoying interruption, and it was no longer adjustable. REI refunded his money. They're pretty good about that type of thing. I dislike plastic on packs.

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Price MSRP: $199.00
Historic Range: $99.93-$138.73
Reviewers Paid: $140.00-$200.00
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