Who the Simba Hybrid Ultra suits
The Ultra is the top of Simba's range and the brand's answer to the question of what it would build without a price ceiling: 34cm, eleven layers, up to 7,300 springs and HeatRelease™ cooling fitted as standard rather than sold as an upgrade.
It makes sense for two specific buyers. The first is the committed hot sleeper who has tried cooling covers and gel foams and still wakes up overheating, this is the most thoroughly engineered cooling mattress in the range. The second is the buyer who wants the plushest surface Simba makes and is not price-sensitive. Everyone else should look hard at the Hybrid Pro, which delivers most of the support for roughly half the money.
Construction and materials
Eleven layers across 34cm. A Stratos® cool-touch cover; the FusionCool™ comfort layer blending wool, bamboo, charcoal and kapok; HeatRelease™ graphite strips; two layers of Simbatex® foam; a PureLift™ layer of latex and coconut for springy support; two layers of Aerocoil® microsprings in thirteen zones; a stabilising CertiPUR® core; an extra layer of up to 2,500 Aerocoil® springs; the SupportCore™ base of up to 1,000 pocketed steel springs; and a CertiPUR® foam base with a recycled-yarn cover.
Four sprung layers and two distinct natural comfort blends is more construction than any other mattress we have catalogued. Whether it is £1,100 better than the Pro is the real question, and for most sleepers it is not.
Comfort and support
We score the Ultra 9.5 for comfort and 9.3 for support, the highest marks we have given on both counts. Simba calls the feel plush, and the depth of spring layering means that plushness never becomes sinking: the surface gives, the PureLift™ and microspring layers respond, and the steel base holds the line. Side sleepers and back sleepers who want a soft surface without sacrificing alignment are the natural audience.
Front sleepers should avoid it. A plush surface at this depth allows the hips to settle further than front sleeping tolerates, and the firmer Pro is the better match.
Temperature
Cooling is the Ultra's real argument. HeatRelease™ graphite strips are standard here, and Simba claims they start drawing heat away within 20 minutes and keep you up to 4.4°C cooler for up to eight hours (the brand's figures, not ours). They work alongside the FusionCool™ layer, two graphite-infused Simbatex® layers, a cool-touch cover and four open spring layers. If you sleep hot, this is the model in the range built for you.
Edge support and motion isolation
The pocketed steel SupportCore™ base delivers firm edge-to-edge support with no roll-off, and with four spring layers absorbing movement independently, motion transfer is minimal. For couples where one partner is a light sleeper, the Ultra is as good as this range gets.
Durability, trial and guarantee
The mattress is mostly steel and natural fibres rather than foam, which bodes well for how it holds its shape over a decade. The 200-night trial and 10-year guarantee are the same as on every other Simba. Practical warnings: at 34cm you need extra-deep sheets, it will sit high on a divan, and it is genuinely heavy to rotate.
Our verdict
The Ultra is the best mattress Simba makes and the worst value in the range, which are not contradictory statements. Its 6.6 value score reflects £2,399 for a double against a Pro that scores within a tenth of a point on support for far less. Buy it if cooling is your unsolved problem or a plush surface is worth the premium; otherwise buy the Pro and spend the difference on a bed frame.
