Firmness
Firm
Type
Hybrid
Depth (cm)
35
Number of Layers
4
Trial Period (nights)
100
Warranty (years)
5
Price Range
£759 to £1,295
Best Sleeping Position(s)
Certifications
Assessed from the specification published by Mattress Online, captured September 2026, and from regular price comparison across our UK retail partners.
If you need firm support but find truly firm mattresses uncomfortable, this design is a sensible middle path. The zoned Mirapocket springs are firmer in the centre third, which means extra support under your hips, the heaviest part of most sleepers. Above that, a layer of mini pocket springs works like bellows to move air through the comfort layers and reduce motion transfer, helpful if a partner tosses and turns. The UltraGel foam adapts to your shape and, per the listing, is five times more breathable than memory foam, so hot sleepers get some relief too. Yes, it's a chunky 35cm deep, but that depth is where the layered comfort comes from. Buying through Mattress Online, you get a 100-night trial and a 5 year guarantee.
Key Features & what's inside
- Pillow top. An additional comfort layer sewn on top, which means a more luxurious, cushioned feel the moment you lie down. It softens the first impression of what is otherwise a firm mattress.
- UltraGel. A gel infused foam layer that adapts to your shape and movements, distributing your weight evenly. According to the listing it's five times more breathable than memory foam, so it should hold less heat.
- Mini Pocket Springs. A layer of 1,000 mini pocket springs that work like bellows, pushing air through the comfort layers as you move. They also help decrease motion transfer, so you feel less of a restless partner.
- Mirapocket Springs. The main support unit of 2,000 Mirapocket springs, zoned so the centre third is firmer. That means greater support under your midsection and encouragement towards better spinal alignment.
Layer details from mattressonline.co.uk product page, September 2026.
Who's it NOT for?
Lightweight side sleepers may find the firm core a little unyielding, even with the pillow top. Owner feedback also flags the depth and weight as practical considerations: at 35cm it needs deep fitted sheets, and it's awkward to rotate or move on your own. Fans of a soft, sink-in feel should look elsewhere.
Silentnight UltraGel 3000 Mirapocket Box Top Firmer Mattress
Across 179 reviews on the mattressonline.co.uk product page, rated 4.7 out of 5, owners commonly describe an exceptionally comfortable, supportive sleep, with several mentioning pain relief from the softer-comfort-over-firmer-core design. The recurring practical gripe is the mattress's depth and weight, which affect bed linen choice and handling.
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How firm is the Silentnight UltraGel 3000 Mirapocket Box Top?
It's rated firm. That said, the pillow top and UltraGel foam layer give the surface a softer, more cushioned feel than the firm core alone would suggest, so it suits sleepers who want solid support without lying on something hard.
How many springs does the UltraGel 3000 have?
The kingsize contains 3,000 pocket springs in total: 2,000 zoned Mirapocket springs in the main support unit plus 1,000 mini pocket springs in the comfort layers. Spring counts vary with mattress size, so smaller sizes will contain fewer.
Does the Silentnight UltraGel 3000 come with a trial period?
Mattress Online lists a 100-night trial on this mattress, along with a 5 year guarantee. These are the retailer's own terms, so check the conditions wherever you buy.
How deep is the UltraGel 3000 mattress?
It's 35cm deep, which is a substantial mattress. You'll likely need deep fitted sheets, and owner reviews mention the depth and weight make it harder to handle than a standard mattress.
Is the Silentnight UltraGel 3000 good for hot sleepers?
It has features aimed at cooler sleep. The UltraGel foam is described on the listing as five times more breathable than memory foam, and the mini pocket springs work like bellows to move air through the comfort layers.
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