Whether you’re hanging around waiting for your race to begin or trying to warm up after an outdoor swim, a hot beverage can be a godsend. That's when a thermos flask comes in.
From light and compact flasks that are easy to carry with the rest of your gear to large containers that can store a large supply of tea and coffee, there are plenty to consider.
Below, we've compiled a list of the best thermos flasks on the market. Picks are based on in-depth research, analysis of consumer reviews, industry knowledge and value for money.
How to choose a good thermos flask
When choosing the flask that works best for you it’s important to consider how much you plan on drinking, how long it will keep your drinks hot or cold in its vacuum seal, the size of the flask and how it will fit alongside the rest of your gear.
Of course, you also want to check whether it comes with a cup or simple opening for easy drinking.
Best thermos flasks to buy in 2022
Thermos Light and Compact Flask
If you have a long day of racing or training coming up, or an extensive amount of travelling to get to your event, this thermos flask is especially ideal as it can retain the temperature of any liquid that's poured inside.
Pop in your coffee first thing and Thermos says it'll stay hot for 14 hours, while cold drinks are said to stay chilled up to 24 hours as well.
Either way the flask is said to be easy to handle as the outer surface will be cool to pick up with piping tea inside.
It's made with a special push bottle stopper that is designed for an easy and convenient pour, and it has a capacity of 350ml.
DrinkPod Capsule Flask
This colourful capsule from the DrinkPod store is a handy and compact container that should be easy to store alongside the rest of your training gear, so you can pack it with your wetsuit without feeling weighed down.
At just 250g it can hold a capacity of 200ml in the vacuum insulated flask and is said to be able to retain the temperature for up to six hours when it comes to hot drinks and 24 hours if you're storing something cold. It also promises to be leak proof.
Yeti Rambler Bottle
This is a sleek and slimline thermos flask from Yeti that should slide snugly into your backpack, ready to be pulled out when you need some extra comfort come race day.
Designed to fit in most cup holders so you can even keep it close by in your car. It's available in two sizes, which include 354ml and 532ml options.
Yeti says it's vacuum-sealed, leakproof and will keep your hot drinks hot and cold drinks cold for hours (but there's no official time claim), so it's a versatile flask whatever you have planned.
Hydro Flask 21oz Standard Mouth
Available in a range of vibrant colours that include pacific and seagrass, you're unlikely to overlook this flask and leave it behind when you need it most.
It has a handy hook on the lid, which means you can hang it up in plain sight, and is designed with a durable stainless steel material so that it can handle knocks and bumps.
It also has a powder coating, giving it that extra bit of grip to make sure it doesn't fall mid-drink. It's said to be able to keep hot liquids at their desired temperature for up to 12 hours and cold drinks chilled for up to 24, and holds a sizeable volume of 621ml.
Primus Trailbreak Vacuum Flask
If you're feeling thirsty and know you have a long, hard day ahead of you, this Trailbreak flask from Primus holds an impressive one litre of liquid.
Although it's a sizeable container it's been designed with a tapered bottom to help you push it down into your backpack and is said to have a reliable grip so it will stay firmly in your hands when in use.
The lid also doubles up as a cup with a separate nozzle so you can keep your drink sealed and retain the temperature while you sit back with your cuppa.
CamelBak Flask
A convenient container, this CamelBak flask weighs a claimed 454g and holds 473ml of liquid, which is better than some other options and enough for a decent caffeine fix.
Ticking all the boxes for a reliable thermos flask, CamelBak says it's leakproof and also fits in most cup holders. It's also designed to be used one-handed thanks to the smart lever on the side.
Nordisk Stainless Steel Drinking Bottle
This slick thermos flask is just 23cm tall but holds a sizeable amount of hot tea or coffee, with a potential capacity of 500ml. It's made from stainless steel, which means you won't have to be too delicate with the container thanks to its rugged construction.
It even comes with a handy carabiner so you can hang it from your backpack to save space, though it doesn't offer any leakproof claims or give any time estimates for how long drinks will stay cold or warm.
Jack Wolfskin Kolima Thermos Flask
Perfect for sharing with a fellow racer or training partner, this flask holds one litre of liquid and comes with two cups conveniently built into the lid. It has an additional screw top to retain the temperature, which is said to help keep hot drinks steaming for 12 hours and cold drinks chilled for 24 hours.
It also has a grippy section of the flask that's designed so you can hold on tight while pouring your drinks to avoid any accidental spillage.