Insulated, stainless steel beer growlers are awesome for camping. But with so many to choose from, which is the best? We put five to the test.

The five contenders.

Time was, if you wanted beer while camping, you brought some cans (and maybe a cooler). But a walk around this year's Outdoor Retailer Show revealed an unmistakable trend: insulated, stainless steel beer growlers from outdoor brands are multiplying like mushrooms after hard spring rains. Combine that with the exponential growth in craft breweries nationwide, and you've got a recipe for fresh-from-the-tap beer on any adventure (ok, clearly not ultralight trips, but still).

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But how to choose? Which to buy? We set our interns (all over 21!) on the grueling task of drinking a bunch of local craft beer from our neighbors at Upslope Brewing Company to find out. Here's their report.

The mighty interns preparing for battle.

The mission

Take some growlers on the trail, rough em’ up, let them sit in the sun for 24-hours, and then find out which is the very best outdoor growler.

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The Contenders

We invited every company currently selling 64-ounce, insulated growlers to contribute a sample to our test. These five took up the challenge (Stanley wanted to, but their model won't be out until fall).

DrinkTanks 64 oz. Growler

This contender has a long, sturdy handle to grasp while hiking or pouring. Its clamp-on lid has a double-bail locking system to prevent leakage. For an extra $45 and 11 oz., you can buy the Keg Cap, which uses CO2 cartridges and a hose to let you treat your growler like a personal keg (side benefit: it helps preserve the beer by letting you inject more CO2 after tapping). But given that DrinkTanks doesn't recommend transporting your beer with this accessory, we opted to test the growler without it. Party bonus: 12 color choices. ($69; 2 lbs. 8 oz., drinktanks.com)

KegWorks Double-Walled SS Growler

This simple, smooth, stainless steel growler has a flip-off clamp top with a silicone gasket to keep your beer carbonated. Its main virtue, at first glance, is it price. But will it hold up to the competition? ($39; 2 lbs. 2 oz.; kegworks.com)

Innate Craft Growler

This growler is one of two with a screw-on lid. Pro: screw them on tight to preserve carbonation. Con: They're sometimes difficult to unscrew. There's also an easy-to-carry handle mounted on the top. It's short and fat, and looks like a coffee pitcher with a screw-off lid. ($50; 1 lb. 14 oz.; innate-gear.com)

MiiR 64 oz. Vacuum Insulated Growler

The lid is a clamp-on like that of the SS Growler; however, this growler has a conveniently narrow top to pour your beers from, and it comes in a few different colors. Miir also gives you a reason to feel good about drinking beer: With each purchase of their growler, they provide a person in need with a year of clean water. ($60; 2 lbs; miir.com)

Hydro Flask 64 oz. Beer Growler

The second growler in our list with a screw on lid. The seal on this lid (like the Innate Growler) prevents leakage, but must be twisted on tightly to be safe. This simple model is the lightest in our test, by a few ounces. ($55; Weight: 1 lb 11 oz.; hydroflask.com; buy it)

The face-off

We walked over to our neighbors at Upslope Brewery who generously filled all of these growlers with their Upslope Pale Ale (abv: 5.8%; IBU: 36).

Lab manager, Mara Miller tested the beer's original temperature. All of the freshly tapped Upslope Pale Ales started out at about 43°F and were totally sealed when we left the brewery.

We then loaded the growlers into our packs, and took them for a hike in Chautauqua Park in Boulder, shaking them up while we climbed to really put them to the test.

(NOTE: We also brought an extra growler full of beer to sip at the end of our hike, for scientific purposes only.)

After the hike, we stored the five closed growlers outside for 24 hours. The temperatures ranged from chilly at night (45°F) to sunny and warm in the afternoon (about 70°F).

Chad demonstrates his discerning palatte.

Finally, we headed back to Upslope Brewery for the hardest (and best) part of the project: the blind taste test. Upslope Head Brew Master, Sam Scruby, lent his professional palette to the three interns' opinions.

The Results

Sorry, internet: no disastrous fails here. “I have seen many good beers become oxidized and flat, even in just a 24 hour period,” said Brew Master Scruby, “but the growlers tested did a great job preserving the flavor of the beer and retaining the carbonation." All the stainless steel insulated beer growlers we tested gave us very drinkable brew after 24 hours (including time in the sun and being bounced around in a pack). We saw no leakage from any of the growlers, but, with the help of our master brewer, we were able to tease out the ways in which each one was subtly different. And we went ahead and ranked them, because what good is a test without rankings?

#5. Most Pourable: DrinkTanks 64 oz. Growler

DrinkTanks 64 oz beer Growler ($69; 2 lbs. 8 oz., drinktanks.com)

Style-wise, this growler is the Abercrombie model of the crew, with an awesome side handle mounted for easy carrying and pouring, and a wide variety of colors to choose from. But after our 24-hour test, this guy was the warmest of the five growlers (by a tiny percent), and a little bit flat as well. We gave the Keg Cap a go afterwards, and the mini CO2 cartridge made it easy to pump out this beer with a refreshingly crisp fully carbonated taste. So if you're willing to shell out the extra dough and carry the extra weight, this one makes for a great party option.

#4. Most Affordable: KegWorks Double-Walled SS Growler

KegWorks Double-Walled SS Growler ($39; 2 lbs. 2 oz.; kegworks.com)

The SS Growler is one that you will find often at your local (hiker-friendly) breweries. It was nearly half the price of all the other growlers, and maintained the taste and the temperature for a cool delicious beer on the trail. While the aroma and the carbonation weren’t altered much in this growler, there was some flavor loss in the 24-hour wait. This growler is available for purchase at Upslope Brewery, and it will definitely do the trick.

#3. Lightest: Hydro Flask 64 oz. Beer Growler

Hydro Flask 64 oz. Beer Growler ($55; Weight: 1 lb 11 oz.; hydroflask.com)

When it came down to the final three growlers, the differences were so slight, even Brew Master Sam had trouble picking out the best. The HydroFlask growler held its own, keeping an incredibly fresh taste and a nice temperature beer to enjoy while on the trail. The only minuscule difference that we noticed in this growler, compared to the rest of the pack, was that it had a weaker aroma (which is where beer gets most of its flavor), but was still totally carbonated and drinkable. We do like that it's the lightest of the bunch, though if you're packing in beer, what's a few ounces in your growler? [Buy it]

#2. Best Value: Innate Craft Growler

Innate Craft Growler ($50; 1 lb. 14 oz.; innate-gear.com)

By the time we were ranking first and second place, we had to really do some on-the-job drinking. Both the Innate and the Miir growlers seemed practically fresh from the tap. The most minute detail we could find to select our victor, was that despite being perfectly chilled and carbonated, there was a tiny difference in the flavor, which you could tell from the lacing in our glasses. While the lacing was still intricate and complex, the tiny bit of carbonation and flavor that was lost was noticeable along the glass (only to the wisest of the beer samplers). And given that the Innate is the second-cheapest, second-lightest, and second-best flavorwise, we feel good calling it the best value of the bunch.

Note: The Innate (#2) and the HydroFlask (#3) beer growlers both had a screw on lid to keep the pressure tight. This helped both beers stay very carbonated, but we must note that our blind taste-test assistant, Mara Miller, needed some help to unscrew both of these tanks after they had been shaken and warmed over the 24-hour test period.

#1. Beer-Snob's Pick: MiiR 64 oz. Vacuum Insulated Growler

MiiR 64 oz. Vacuum Insulated Growler ($60; 2 lbs; miir.com)

After thoroughly testing every one of the growlers, our decision was unanimous, everyone voting for the same cup. Something about the temperature, the carbonation, the flavor, the aroma, and the beautiful lacing, seemed like the glass had been filled straight from the tap. When it comes down to selecting your hiking growler, the final choice is not an easy one, but when it came down to the tiniest of details, the MiiR won our battle. This growler was stylish, with an easy-to-open cap, and a basically perfect beer waiting to sip after sitting in the sunshine for 24-hours.

Post-script

We accidentally let these bad boys all sit in a warm car for another 72 hours. While not cold and crisp, all of the beer left in these growlers was still at a drinkable temperature and moderately carbonated. Moral: Get one of these guys so you can take your beer camping.