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Reviews > Packs > Frameless Backpacks and Day Packs > Outdoor Products Amphibian Weather > Test Report by Derek Hansen


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Outdoor Products — Amphibian Weather Defense 20L Pack

Test Series by Derek Hansen


NameDerek Hansen
Height5' 10" (1.78 m)
Weight170 lb (77 kg)
Chest40 in (102 cm)
Email Address pix-obfuscated
City, State, CountryFlagstaff, Arizona, USA


I am a lightweight backpacker with a typical overnight pack weight of 15 lb (7 kg) and a multi-day weight of 20 lb (9 kg), each of which includes food and water. Because I pack less than 20 lb (9 kg), I prefer lightweight trail-running shoes. I prefer backpacking with a hammock as part of my sleep system.


Manufacturer Outdoor Recreation Group, California, USA
Year of Manufacture 2012, made in USA
Manufacturer’s Website
Listed Features

None yet listed.

Manufacturer Recommendations

None yet listed.

Specifications What They Say What I Say
Weight N/A 24.25 oz (687 g)
Dimensions N/A 25.5 in (65 cm) tall unfolded
16 in (41 cm) (top) x 10 in (25 cm) (bottom, when flat)
Volume 20 L (1220.5 cu in) 20 L (1220.5 cu in )
Colors Blue; Black/slate


23 Oct 2012


The Outdoor Products Amphibian Weather Defense Pack is a 20 L (1220.5 cu in) day pack with padded shoulder straps, an adjustable sternum strap with plastic buckle, three outer zipper pockets/sleeves, and a roll-top enclosure with two adjustable buckle clips. Between the shoulder straps is a carry handle with a rubberized grip.

The pack is top-loading with one main compartment. Some describe these pack styles as "stuff sacks with shoulder straps." This is only partially true with the Amphibian pack as this pack also has a sewn-in plastic frame sheet with a back padding. The back padding is actually two contoured and shaped strips of padding with 3D mesh.

The back padding and frame sheet are sewn into the pack. The entire pack construction appears to be welded and taped for the most part.

The three outer, zippered pockets are small. The two side pockets mirror each other and are diamond shaped and have a 6 in (15 cm) weather-resistant zipper. These side pockets have no gusseting and are, essentially, sleeves, roughly 4.5 in (11 cm) at the widest point in the diamond and about 9 in (23 cm) tall.

The back pocket has a weather-resistant zipper and a plastic mesh covering, so the pocket is "breathable." I would also call this pocket a "sleeve" as there is no gusseting and the mesh does not stretch. This pocket is roughly 9 x 9 in (22 x 22 cm).

There are two gear loops on the base of the pack, separated by a reflective rectangle. There is only one gear keeper near the top of the pack. The keeper is a length of shock cord and cord lock/toggle.



The pack has certainly caught my eye with its sleek lines and colors. I am testing the black pack and it has slate tones for the side sleeves and orange highlights. It is a very good-looking pack. I was also pleased to find a frame sheet in the pack. While the sheet is not removable, it does add some rigidity and form to what would otherwise be a "floppy" stuff sack. The material and fabric is also very durable and substantial, giving this pack some substance.

One thing noticeably missing from the pack is a waist strap. While I believe it would be difficult to carry really heavy loads in this pack that would necessitate weight displacement on the hips, having a waist strap does help in stability and prevents the pack from swinging back and forth. More on that later.

After the initial inspection, the first thing I did was see how much I could fit in this pack. I take pack volume for granted at first, knowing that many manufacturers include exterior pockets and extension collars in the overall volume, which can be misleading. Since this pack doesn't really have pockets that add volume, the capacity is really limited to the main compartment.

I was pleased to find that I could easily fit my ultralight pack list for a simple summer overnight into the pack.



  • 40°F (4°C) HammockGear down top quilt
  • 20°F (-7°C) HammockGear down under quilt
  • Grand Trunk Nano 7 Hammock
  • DutchWare Whoopie Hook with straps and slings
  • GoLite Poncho Tarp
  • 6 aluminum stakes
  • Sleep clothing (balaclava, head buff, socks, Marino wool sweater)
  • Cook gear (cat can stove, 4 oz (113 g) denatured alcohol, 'foon', silicon gripper, pot cozy, windscreen, GSI Soloist stove)
  • Ditty bag (first aid kit, toothbrush/paste, water treatment, personal hygiene, bear bag hanging kit)
  • Fire starter/survival knife
  • Compass
  • Rain gear top
  • Headlamp
  • 1.5 L (1.5 qt) water*
  • 3 meals (breakfast, lunch, dinner, + snacks) in a bear bag

TOTAL WEIGHT: 10.5 lbs (5 kg)

Since I could fit everything I need for a simple overnight trip, I was really debating whether or not I could take this pack for a backpacking trip this fall. The top quilt wasn't going to be enough, but I still had some volume left in the pack that I could use up with some extra warm-weather gear. I also considered simplifying my shelter to just a tarp and then sleep on the ground. I could easily exchange the hammock for a Therm-A-Rest NeoAir pad and combine the top and bottom quilts with a beefier winter quilt and still be okay.

But as I'm pretty averse to sleeping on the ground, if I can help it, I decided to see if I could squeeze in a 20°F (-7°C) top quilt instead of the summer quilt and make it work for the fall.

It fit!


I kept all the gear from the summer list but exchanged the following:

  • 20°F (-7°C) Jacks "R" Better wearable top quilt
  • HammockGear Cuben Fiber "winter" tarp
  • 3 L (3 qt) water*

TOTAL WEIGHT: 14 lbs (6 kg)

*NOTE 1: As the pack has no side pockets or accommodations for water bottles or hydration systems, I had to devise my own. I sewed a "hydration sleeve" with buckles that could "hug" the Amphibian pack and allow access outside the pack. Since this is a waterproof pack and I'm using and expecting the pack to keep my gear dry inside, the last place I wanted my water bottles was inside the pack.

NOTE 2: For my winter gear, I was also expecting to wear more insulation and carry a few clothing items in coat pockets (e.g., gloves) instead of in the pack.


Since this was a "waterproof" pack, I wanted to really test the listed capacity of the pack. I figured the easiest way to do this would be to fill up the backpack using a 1L Nalgene bottle. I filled the pack up with 18 L (~19 qt) of water to the top of the shoulder straps leaving several inches/cm for the roll-down top. Adding two more liters/quarts would easily fit in this pack, which satisfied me.


On the other hand, the pack leaked. At the base of the pack, I noticed it was soaking through, right where the back frame sheet is sewn to the pack. Everywhere else the pack stayed dry. My guess is poor seam sealing at key points.



I went on a short, 1-mile (1.6 km) hike with my family and brought along the Amphibian pack, loaded with my "summer" gear. At only 10.5 lbs (5 kg), the pack was hardly noticeable on such a short hike. Getting water meant taking the pack off and getting into my "leech" bag on the outside. I can adjust the shoulder straps so the pack rides high on my shoulders. When I do this, the pack is fairly solid and doesn't rock back and forth with the load. However, when I drop the pack so it rests more on my back and hip/pelvis, I noticed some rocking side-to-side. This is where a small hip/waist strap would really come in handy.

The frame sheet and back padding are really helpful. I have a few frameless packs that lack any kind of padding or frame sheet and once packed, they really "barrel" out. The frame sheet in the Amphibian pack really helps "square" up the pack, making it ride snugly to my back.


I think my biggest letdown with this pack is the lack of water storage. For day hikes, trail runs, or even if I try an ultralight backpacking trip, I need to carry water. This pack was designed for the first two trip types, yet it really lacks good hydration options. I could throw a water-tight bottle inside the pack for some trips, but when I have gear inside that I'm trying to keep dry, this isn't the best option.

So, unless I skip the water, I'm left with a few options: use a secondary carrier just for water, find a way to strap water directly to the pack, or carry bottles in my hand.


Another oddity with this pack is the two gear loops on the bottom. Gear loops are great, but there is only one gear attachment on the top of the pack. I suppose the second loop adds some symmetry to the pack and I can clip something there, but I'm at a loss as to what. Between these two gear loops is a small reflective rectangle. The reflector is a nice touch, but it isn't really enough for me to feel justified in considering this a highly visible pack for safety. Maybe if some reflective striping were adding along key seams, the reflector would add some visibility for night running or hiking.

The last thing I felt was missing on this pack was a whistle lock on the sternum strap. I know, it's not a law that all new packs need this gimmicky piece of gear, but I've really grown attached to this emergency item and think they are a nice touch on a pack.


It's a nice pack that looks sexy. I'm pleased that I can stuff my ultralight backpacking gear inside, so I know it will easily accommodate any day hikes I take.

PRO—Great design and colors. Good volume for size/weight. Nice roll-top enclosure. Great frame sheet and suspension support.

CON—No side pockets or accommodation for water bottles or hydration systems. No waist belt. Waterproofing needs work. Twin zipper pockets are small and somewhat unusable.


8 Jan 2013


Oct 26-27: Kachina Trail, Arizona. I went on a 13 mi (21 km) backpacking trip with my troop on the San Francisco Peaks. The high temperature was around 50°F (10°C) and the overnight low was 30°F (-1°C). Elevation was 9,200 ft (2,800 m).

Nov 2-3: Upper Lake Mary, Arizona. I joined the older boy scouts on a short 4 mi (10 km) backpacking trip near Lake Mary. The high temperature was around 50°F (10°C) and the overnight low was 35°F (2°C). Elevation was 7,000 ft (2,100 m).

Nov 12: Buffalo Park, Flagstaff, Arizona. I went on a 6 mi (10 km) day hike with my family. The temperature was in the 40s°F (~5°C). Elevation was 7,000 ft (2,100 m).

Nov 24: Picture Canyon, Flagstaff, Arizona. I went on a 4 mi (6 km) day hike with my kids. The temperature was in the 50s°F (~10°C). Elevation was 7,000 ft (2,100 m).

Dec 7: Old Caves Crater, Flagstaff, Arizona. I went on a 2 mi (3 km) day hike around the cinder cone. The temperature was in the 50s°F (~10°C). Elevation was 7,000 ft (2,100 m).

Dec 13: Near Old Caves Crater, Flagstaff, Arizona. I decided to play hooky and go trail running to bag some cinder cone peaks near my home, totaling 5 mi (8 km). The temperature was in the 50s°F (~10°C). Elevation was 7,000 ft (2,100 m).



I have really enjoyed using the Amphibian pack, especially when I pushed its limits on a backpacking trip with my Boy Scout troop in October. I really wanted to test this bag's capacity and comfort on a multi-day trip when I could safely carry enough gear to be warm before the temperature dropped too much. On this trip, I carried my gear listed earlier in this report, but I brought along two top quilts just to be safe as it was predicted to get as low as 15°F (-10°C) overnight. Most of the parents were worried the scouts would be too cold, but ironically, it was my second adult leader who forgot his sleeping bag! Thankfully he brought extra coats to share with the scouts in case they forgot theirs (!), and I loaned him my second top quilt. I was thankful the pack was able to carry all the gear I (we) needed that night, for in a twist of fate, the temperatures inverted and we stayed warmer on the mountain than parents fared down in town.

For the most part, the pack rode fine on my back and simple adjustments to the shoulder straps would alleviate any discomfort. I brought along a small hip pack where I stored some of my extra clothing and this added some "hip lift" to the pack. I also had to carry an extra bag for my water, which I didn't want to carry inside the waterproof bag.


I also packed the pack to its limit on another backpacking trip in November. Instead of two sleeping bags, I brought along one thicker one. The roll-top enclosure on the backpack really helps to expand or collapse the pack to meet the requirements of the contents.


In fact, on a day hike to Picture Canyon, I carried only minimal gear, to include a hammock, first aid, and snacks (along with other odds and ends). The frame sheet really helps keep the pack from wrinkling up.


I don't mean to repeat myself, but my biggest complaint is still the lack of pockets or support for water storage. On nearly all my hikes and trips I have brought along a separate bag to hold my water. On one trip in December, I was trail running and I wanted the pack to be as close and snug to me as possible, so I opted to leave the extra pouch at home and keep my water bottle inside the pack. Besides the risk of water spilling, the only inconvenience is the need to stop, remove the pack, and dig around to get the water.


The other thing I noticed on this trail run is that the sternum strap is at its maximum expansion and I could feel my chest tightening when I was breathing. My chest measurement is 40 in (102 cm) where the sternum strap connects. The sternum strap really helped the shoulder straps to stay on my shoulders, but the tightness was annoying. And with only a thumb length left on the strap, there was little to hold to make any adjustments.

The side pockets are small and tight. I store my hammock straps on one pocket, typically, and a few stakes in the other. A headlamp often finds its way in the small, center mesh pocket. It's nice to have some organization options, even for just the little gear items.

I've used the keeper straps for my trekking poles on numerous occasions and I really like the toggle and elastic cord combination. My poles have stayed attached without any jiggling when running or hiking.


I like the pack's looks, compression, and sturdy frame sheet that helps balance the load and prevent the pack from barreling out with full loads. The capacity has been just fine for ultralight backpacking, and more than adequate for trail runs and day hiking.

I think the only thing really missing are some expanded exterior pockets, particularly for a water bottle.


13 Mar 2013


I've taken the pack on three additional day hikes, totaling more than 8 miles of hiking. All of these trips were close to home in Flagstaff, Arizona, elevation 7,000 ft (2,133 m).

I also took the pack on a family trip to Disneyland, California, in February, where I spent three days walking and running all over the park with my family. This was a great test of the pack as I used it to store water, clothing, and pack lunches.



One thing I did notice about the pack that I didn't realize before is that the folding top buckles can clip to each other, like other roll-top bags I've used. This "feature" has been really nice when I didn't pack as much inside. Using the roll-top, I could squeeze out more space and then clip the top to itself, and then clip the two side straps to each other, acting as a compression strap.


At Disneyland the pack saw a lot of movement as we used the pack for just about every loose item we took with us in the park. After I unloaded the lunch, the pack's volume decreased dramatically and I was able to compress the pack nicely with the strap system I found. The pack has held up nicely after tossing the pack into the floor of multiple roller-coaster rides across the park.

My one critique continues to be the lack of side pockets for water storage. It would have been very handy at Disneyland to just reach and grab water to satisfy my own and my children's wants, but instead I had to take the pack off, unbuckle, and unload the water from the pack.

PRO—Durable, great compression.

CON—Lack of external water storage.

I would like to thank Outdoor Products and for providing me with the opportunity to test this product.

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