Selling out fast: Simba cheapest cooling mattress drops to £261

Simba Simbatex Cool Mattress on a wooden bed frame in a beige bedroom on a sunny day — (Image credit: Simba Sleep)

A second summer heatwave is upon us and if your bed turns into a giant foam oven at night, I recommend investing in a cooling mattress that wicks away heat fast. Simba makes some of the comfiest and coolest beds I’ve tested, and its cheapest cooling mattress, the Simba Simbatex Cool Mattress, is down to £261 (was £349) at Amazon for Prime Day members. It also has a machine washable cover to get rid of summer sweat.

The Simbatex Cool Mattress was launched in March and is made from four layers of certi-PUR graphite-infused Simbatex foam. This material is breathable and fast to dissipate heat. So the main consideration is the height. At 23cm (9 inches), it’s slightly shorter than the average bed-in-a-box, so I’d be wary of heavier bodies (240lbs+) receiving enough pressure relief to sleep comfortably.

Otherwise, at £299 for a double the Simbatex Cool is excellent value for money among this year’s best Amazon Prime Day mattress deals. Not an Amazon Prime member? No problem – Amazon is offering a free 30-day Amazon Prime trial, so you can sign up today and access big price drops on all of this year's best Prime Day deals.

Cooling, supportive and affordable

There are only seven double sizes left on Amazon for the Simba Simbatex Cool Mattress, and it isn’t hard to see why this budget bed-in-a-box is close to selling out on Day 1 of Prime Day 2026…

In the UK, Simba makes some of the best mattresses for every type of sleeper. Every Simba mattress we’ve tested has walked away with a score of at least 4 out of 5, and I’ve been sleeping on the Simba Natural Hybrid Apex (a knock-out organic mattress, on sale from £1,109 at Simba) for two years and can’t fault it.

A woman with blonde hair sits peacefully on the Simba Simbatex Cool Mattress with her eyes closed as she holds a cup of warm tea — (Image credit: Simba Sleep)

The Simbatex Cooling Mattress comes in a medium-firm feel, and looking through verified customer reviews on Amazon (our official review is coming soon) it seems to be on the firmer side.

So based on that real-life feedback, the 23cm depth, and the construction of the mattress itself, I’d mainly recommend this mattress to back and stomach sleepers who fall in a normal weight category (under 230lbs each).

Side sleepers might need to partner it with a cooling mattress topper to add a bit more cushioning around the hips and shoulders. I’ve added some recommendations for you below.

Overall, few sleep brands come close to Simba for performance versus price, especially when you consider the amount of cooling tech you’re getting in a double size mattress here for £261. If you like the look of the Simbatex Cool Mattress, I’d buy sooner rather than later as this one could sell out soon.

Topper deals to soften up firm beds for less…

Want more deals? See all mattress topper offers at Amazon

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Claire is a Certified Sleep Science Coach and the Managing Editor of Sleep at Tom's Guide. She oversees our rigorous mattress testing procedures, and our buying guides and mattress rankings. Claire has over 16 years' product review experience and is connected to a wealth of globally renowned sleep experts including mattress designers, neuroscientists, and board-certified sleep doctors. She is also our in-house expert on Saatva, DreamCloud, and Nectar Sleep. Claire is certified to advise people on how to choose a mattress that suits their needs and budget, as well as helping them to create a nighttime routine and bedroom environment that helps them sleep better. Previously, Claire reported on sleep and wellness tech for T3 and TechRadar.