MondoKing 3D YT

Thermarest MondoKing 3D Self-Inflating Camping Mat

Thermarest MondoKing 3D Self-Inflating Camping Mat

We test out the Therm-a-Rest MondoKing 3D SIM on a cold winter camp.

Review Score

A great self-inflating mat. For the large size, it's probably best for car camping.

Our Score: 9.5/10

We've given the Thermarest MondoKing 3D Self-Inflating Camping Mat the Thumbs Up award.

GOWTK Thumbs Up Award
Value for MoneyQuality

The good

  • The MondoKing 3D is a good sized Self Inflating Mat with insulation to help keep you warm on those cold nights.

The not so good

  • It is more expensive than cheaper SIMs... but you get what you pay for ;-)

This was a hands-on product review. The product was supplied to us to test and conduct the review.

Price Guide

The best price we've found so far is £216.75.

Thermarest MondoKing 3D Self-Inflating Camping Mat Videos

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Thermarest MondoKing 3D Self-Inflating Camping Mat Photos

MondoKing 3D YT

MondoKing 3D YT

Our Review

Therm-a-rest is a brand synonymous with great Self Inflating Mats that provide fantastic insulation.

So, naturally, I was elated when they decided to send me their MondoKing™ 3D SIM.

Therm-a-rest MondoKing 3D SIM - Large

Therm-a-rest sent over their larger version of the MondoKing 3D, which is perfect for our camping, which we mainly do with the car.

As with most SIMs, the Therm-a-rest MondoKing 3D SIM has two valves at the top for inflating and deflating.

you should let it unroll at home first

I hadn't unrolled it before taking it on our early February camp. This is not the most sensible thing to do of course, as you should let it unroll at home first, as it can take a while to inflate after being packed for so long ;-)

However, after leaving it some considerable time, and giving it a few puffs of air, I had the MondoKing inflated.

A good sized SIM

Certainly, this SIM is a good size. It had plenty of room even if I rolled around a bit in my four-season sleeping bag, plus it was quite thick. Almost a few inches when inflated. (10cms is the official specs)

This is the largest Self-Inflating Mat that Therm-a-rest currently make.

Here's how thick it 'self-inflated'. You can, of course, make it thicker by blowing in some more air.

Another Point of View

Shell also has spent time sleeping on the MondoKing 3D.

I found the SIM to be very comfortable and plush. It didn’t feel like you were sleeping on the ground.

One of the best SIMs I have tried. It's also nice and quiet, so it doesn't wake you when you turn over at night. It's much better than a cheap one.

Keeping me warm

The R-value of this SIM is 11.4.

should be good enough down to -40C

According to the specs, this should be good enough down to -40C. Though I wasn't going to test that was the case!

Using it in early February with a 4-season sleeping bag, I didn't feel the cold, despite a frost outside.

I had put down a poncho insulation quilt on the tent floor, so with the additional R-Value of this SIM, it was doing the job quite well.

Rolling up the Mondo King

Putting SIMs away, especially large ones, can take a while, as a lot of air is needed to get out of the valves at the top. The Mondo King 3D was no different.

Unlike other SIMs, this didn't have any compression straps to keep it rolled up. However, I didn't find this a problem, as it stayed together well once the air valves were closed, and I placed it back into its stuff sack.


I've only used this once so far on a cold winter camp, and I've been very impressed with this Thermarest SIM.

It gets the Thumbs Up from us.


So we've been using the Thermarest MondoKing 3D for the past year. I like this SIM.

It's comfortable. It's warm. And it's reliable.

The only downside is that it is harder to pack up than the new 'smart' valves on SIMs from Outwell and Vango. But that's only a minor niggle.

It's taken a lot of punishment over this last year, with both kids and the dog in the tent. And it's still going strong.

This SIM is an investment but is still recommended.


AttributeThermarest MondoKing 3D Self-Inflating Camping Mat
Best Price£216.75
Product Info
Number of Valves2
Re-Inflation PreventionNo