GEAR,  Product Reviews

The best flasks for outdoor swimmers

Robust enough to withstand knocks on the beach and riverbank; sturdy enough for cold hands to grasp; and able to hold enough soup to warm you right through. Omie Dale reviews the best flasks for outdoor swimmers. 

Updated October 2023.

Stanley Classic Trigger Action Travel Mug 350ml


They say: Packed full of ingenious features, the Trigger-Action Travel Mug is the perfect partner from commute to canoe. From hike to city bike. Sip-on-the-go wherever you’re going. It’s durable, stylish, portable, and keeps your drink nice and hot – or cold – for hours. The trigger action lid makes this cup leakproof and easy for one-handed use.

We say: This mug was easy to drink from when on the move, with a simple press of a button triggering the opening of the mouthpiece. With its durable and tough design, it seems like the ideal companion for the hardiest of adventures. The double-wall vacuum insulation ensured my drink was hot for a long time.

Ocean Bottle Sky Blue 500ml


They say: Made from 90% recycled stainless steel, BPA-free plastic, silicone rubber and ocean-bound plastic, our award- winning Ocean Bottle is designed to come along with you at home and beyond. With its double wall vacuum-insulated stainless steel, it keeps your cold drinks cold and your hot drinks hot. For every Ocean Bottle sold we commit to the collection of the equivalent of 1000 plastic bottles.

We say: Not only is Ocean Bottle’s plastic collection a great initiative, the bottle is great too! With several colours to choose from and its dual opening and easy carry loop, it’s definitely one of the more stylish options. As the lid isn’t insulated, drinks won’t stay as hot as some of the other options, but it ensures it still is light when carrying.

Lifeventure TiV Wide Mouth Vacuum Flasks


They say: These solid thermally induced wide mouth flasks come with a clever retractable side handle and removable shoulder strap. The stainless-steel lid can be used as a cup and there’s a second ‘buddy’ cup in the lid. Copper coated for greater heat retention and keeps drinks hot for up to 8 hours or cool for 12 hours.

We say: One of the cheapest options on the list, but without a scrimp on quality. With the choice between 800 and 1000ml, the larger size of this flask makes it ideal for carrying food, or to have enough to share a warm drink with your fellow swimmers. The handle on the side also allows for easy transportation.

Klean Kanteen Insulated TKPro 750ml


They say: Feature-rich versatility in a streamlined form. The TKPro is a high-performance, plastic-free thermal Kanteen. With its integrated double-wall stainless steel cup and 360-degree pour-through functionality, the TKPro features our new TK ClosureTM internal thread design which provides cutting edge thermal performance for both hot and cold beverages. Whether sipping hot coffee or ice cold drinks, the TKPro is your built-to-last solution.

We say: This bottle is great for swim adventures, with its double-wall stainless steel design making it tough and able to keep drinks hot all day. The cup is a generous size for a post-swim warm-up and the 360 degree pour prevents spilling (particularly important with post- swim jitters!). The only thing I would like is a wider bottle mouth.

The Revival Orange, Thermos


They say: The Revival is a replica of one of the original Thermos flask designs, Model 18. Mirroring the original pattern and colourways, The Revival brings the classic and timeless plaid flask back to life. Available in a trio of colour combos, our 500ml retro flask is ideal for everyday use for people on the go. With a 5 year guarantee, this retro flask is festival ready.

We say: You can’t go wrong with Thermos, hot drinks will still be warm enough to drink a day after making them. This retro style reminds us of camping when we were kids, so has nostalgic value as well. Really simple, no-frills design. Maybe a bit too big for a short dip, but good on a day trip providing several hot drinks or a good one to pack into the boot of the car.

Hydro Flask Coffee Flask with Leakproof Flex Sip Lid (473ml)


They say: Perfect for your favourite warm drink, the TempShield® Double Wall Vacuum Insulation will keep your drink hot for hours, so that it is ready for after you come out of the water. The leakproof Flex SipTM lid is easy to use with chilly fingers, you just twist the lid to sip, then twist back to lock. Hydro Flask are made in outstanding quality and come with peace of mind with a lifetime warranty.

We say: Really loved this simple, light and effective flask. The lid was ace for numb fingers and shaking cold hands. The drink was still steam- ing hot hours after filling and in cold air temperatures. Robust and hardwearing it survived a drop onto hard concrete and never leaked. Easy to clean and has a clip for carrying on your backpack!

This is an extract from the December 2022 edition of Outdoor Swimmer magazine, updated in October 2023. If you buy a product through a link on this page we may receive a commission. Read more outdoor swimming gear reviews.

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Outdoor Swimmer is the magazine for outdoor swimmers by outdoor swimmers. We write about fabulous wild swimming locations, amazing swim challenges, swim training advice and swimming gear reviews.