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The Best Thermal Flasks: Our Top 5 Picks

There’s nothing worse than taking a sip from a thermal flask and getting a mouthful of lukewarm coffee. Or a hot drink of water after a long day out in the sun.

And with all the improvements that have been made to insulated water bottles, there’s no reason for you to not have a reliable product.

Before you head to the store, be sure to check out this list of the best thermal flasks on the market!

Read on for descriptions of each product and a buyer’s guide to help you choose the best one for you.

An insulated camping flask for hot or cold liquid. Thermal flasks.

Our Top Picks

Best Overall
Stanley Classic

Budget Option
Hydro Cell

Best Insulation
Zojirushi SM-SA60BA

Best Overall

Stanley Classic

Stanley Classic Vacuum Insulated Wide Mouth Bottle - BPA-Free 18/8 Stainless Steel Thermos for Cold & Hot Beverages – Keeps Liquid Hot or Cold for Up to 24 Hours

When it comes to long days in the great outdoors, there’s no better thermal flask than the Stanley Classic!

A multi-purpose lid works as the perfect mug for your mid-hike break. Allowing you to get your fill without needing to leave the lid open for heat to escape. The double cap design also means this water bottle can keep your liquids cold and hot for a total of 24 hours!

Despite its full one-liter capacity, this thermal flask is perfectly designed for portability. Both the collapsible handle and the circumference of the base allow it to slip in and out of your backpack with ease.


  • Multi-purpose lid
  • Durable
  • Collapsable handle


  • Hand-wash only

Best Budget

Hydro Cell

HYDRO CELL Stainless Steel Insulated Water Bottle with Straw - For Cold & Hot Drinks - Metal Vacuum Flask with Screw Cap and Modern Leakproof Sport Thermos for Kids & Adults (Black 24oz)

Survival in the wild is all about the gear you have and the resources you ration. That’s why buying the best product also means getting what you need at the best price!

Packed with some of the best insulation technology, the Hydro Cell thermal flask is easily the best bang for your buck. Not only does it use the double-walled insulation method, it takes it a step further by adding a copper lining within the vacuum-sealed chamber!

Even with a lid that doesn’t have the best insulation materials, this thermal flask can keep your drinks cold for 24 hours and hot for up to 12!

The large variety of sizes also makes it easy to get the perfect bottle for your needs. Whether you want an easy-to-carry 24-ounce flask or a larger 64-ounce jug, the Hydro Cell brand has you covered.


  • Comes with two caps
  • Triple-walled insulation
  • Comes in lots of sizes


  • Not the best lid design

Best Insulation

Zojirushi SM-SA60BA

Zojirushi SM-SA60BA Stainless Steel Vacuum Insulated Mug, 1 Count (Pack of 1), Black, 20 oz.

The difference between life and death in the wilderness can sometimes be the most minor detail. Like a hole in your backpack, or a thermal flask that can’t stay hot during a long, cold night.

But with the Zojirushi’s triple-walled insulation and air-tight, lockable cap, you’ll never have to worry about your flask’s capabilities. Some reviews even claim the bottle can keep liquids icy cold for three days. And your coffee will still be too hot to touch after six full hours!

All that insulation and its sleek design means this bottle only has a capacity of 20 ounces. But as a hot water bottle during the night or a place to store ice during your trip, this product is perfect.

Plus, the lid can be fully taken apart to ensure your thermal flask is always kept as clean as possible!


  • Tripple-walled insulation
  • Cap can lock
  • Lid disassembles


  • Smaller capacity

Best for Large Quantities

Buzio One Gallon Thermal Water Bottle

BUZIO One Gallon Water Bottle Insulated, 128oz Stainless Steel Water Bottle, 18/8 Food-Grade Beer Growler with Carrying Pouch and Two Stainless Steel Cups, Hot Cold Thermo Canteen Mug, Black

Every survivalist knows that sufficient stores of water are the number one necessity for life off the grid. That’s why the Buzio One Gallon is a must-have item from this list!

When days are filled with the hard work needed to sustain yourself in the wilderness, a simple litre of water won’t cut it. Being able to store a full gallon in a thermal flask that can keep your water cold for up to 48 hours and hot for up to 24 hours, is a game changer.

If you feel like the one-gallon size isn’t for you, The Buzio also comes in an even larger 192-ounce jug, or a slightly smaller 84-ounce one.

It may be a little heavy, but the extra weight is nothing compared to the security it offers! Plus, the soft-grip handle and pouch that it comes with make it easy to carry around.


  • Comes with cups and a carrying pouch
  • Double-walled insulation
  • Comes in other sizes


  • Heavy

Best for Kids

Yeti Rambler Jr

YETI Rambler Jr. 12 oz Kids Bottle, with Straw Cap, Seafoam

Surviving in the wild with kids is no easy task. You need to know that they can take care of themselves, and having their own thermal flask is part of that.

That’s why you need the Yeti Rambler Jr. Its flip-up straw is designed so that even a two-year-old can open the bottle themselves. Yet it’s still guaranteed to not leak on you.

Made from durable, thick-gauge, stainless steel, this flask can handle endless abuse and always look as good as new. Plus, a radiant barrier in the double-walled insulation helps keep your liquids cold for up to 24 hours and hot for up to 12 hours.

The Yeti is a little pricy for the size you’re getting, but all the thought they’ve put into the design and materials means you’re definitely getting your money’s worth!


  • Easy to use
  • Durable
  • Radiant barrier


  • Pricy

Thermal Flasks Buyer’s Guide

A black insulated camping water bottle.

Insulation Types

The double-walled, vacuum insulation is definitely the most popular method used for thermal flasks. It works by vacuum sealing the space between the inner and outer stainless steel walls. That emptiness then acts as a solid barrier between your drink and any outside temperatures.

Some companies have also started adding an extra layer of copper within the vacuum-sealed chamber to increase its insulation capabilities even further!

On average a thermal flask using the double-walled method should be able to keep your drink cold for 24 hours and hot for 12 to 24 hours. The exact time will depend on how well the cap is designed.

There are also copper, air, and foam insulation methods that are sometimes used in lower-quality products. A thermal flask using those insulation materials will only be able to keep your drink hot for six to eight hours and cold for up to 14 hours.


When choosing the right size, the style of your thermal flask is much more important than how much liquid it can hold. Most products come in standard capacity sizes, and the choice between them is just personal preference. But the shape and style of each flask will have a big impact on your mobility.

The handle on a mug-style thermal flask is convenient when drinking but it also makes it much harder to fit them into water bottle holders. If you only plan to use your mug around the house, this isn’t an issue. If you want something you can take with you everywhere, a simple water bottle-style flask is better.

But not all water bottle-style thermal flasks have the same width. Before buying your product, be sure to check its dimensions and think about how you want to use it.


When it comes to thermal flasks, there’s no better material than stainless steel. It’s a better insulator than glass and plastic, it’s more durable than copper and aluminum, and it’s extremely lightweight.

A stainless steel thermal flask.

Stainless steel is also a non-porous material. So it’s easy to clean and more hygienic than some of the other materials that thermal flasks are made from.

The material of the lids can be hard plastic or glass without affecting the design too much. But steel or something else with natural insulation capabilities is better.


Thermal flasks are usually equipped with one of three different styles of lids. First is the chug cap that makes it easier to pour, second is the flip-up straw, and third is the slider lid.

Chug caps are either quick-release or twist-off. When buying a quick-release cap, make sure it comes with a lock and can’t pop open in your bag.

Cheaply made straw caps are not always reliably leak-proof, so be sure to test out the flask before using it. And slider lids are never completely leak-proof. That’s why they usually come on mug-style thermal flasks that aren’t meant for hiking or outdoor activities.

No matter what option you choose, always check the sealing mechanism on your lid. For the best heat retention, you want something with rubber or silicone that can really mold to the edges of the bottle and create an air-tight seal.


Even if you just have water in your bottles, germs from your mouth can lead to mold growth along the inside of the lid. To be safe, you should rinse your thermal flask with fresh water after every other use.

Besides that, a good thorough cleaning should be given to your bottle at least once a week. Before throwing it in the dishwasher, always check to make sure your product is dishwasher safe.

Also, any silicone or rubber parts that aren’t glued in and can be removed should be cleaned separately. Otherwise, there could be bacteria building up without you knowing.

The Best Thermal Flasks Summed Up

Two hikers with thermal flasks in outer pockets on their backpacks.

Even after days in the wilderness, always know your water will be cold and your teas will be hot with one of these top picks of the best thermal flasks!

For information on how to keep yourself hydrated off the grid, check out our article on How to Make a DIY Water Filter With No Tools.