Therm-a-Rest MondoKing 3D Review

The MondoKing 3D is exceptionally comfortable and warm. Just keep in mind that it's large when packed (like most of the foam mattresses in our review), but it is just slightly easier to inflate and deflate than almost all the others we've tested.

Performance Comparison

Comfort

Compared to your standard inflatable sleeping pad or basic air mattress, using the MondoKing 3D is bonafide luxury camping. Vertical sidewalls mean you can utilize the entire 30-inch width and 80-inch length to spread out and sleep like a large king starfish. While this may feel indulgent for camping, it is quite lovely not to feel like you are in danger of rolling off the edge of the mattress. These generous dimensions also provide room for your dog to snuggle nearby.

No matter your preferred sleeping position, the four-inch foam core of the MondoKing can easily be adjusted to perfect firmness with the separate one-way valves (one for “in,” one for "out"). Because it is easier to release a little air with a simple twist of the conveniently labeled “out” valve than it is to add air on the fly, we recommend adding extra air before you settle in for the night. At that point, you can release air, as necessary, for the perfect level of comfort.

The MondoKing uses StrataCore Foam, essentially a thermal foam core sandwiched between ridges of foam and air. This gives the surface a unique wave-like texture and makes it much easier to roll up. It also offers a substantial weight reduction from the previous version of this mattress. We did not notice the ridges at all when using the MondoKing, and the soft polyester cover provides a non-slippery, non-sticky place to lay a cheek that is both breathable and quiet to sleep on top of. Many of the mattresses we tested are comfortable, but this is one of the best.

Ease of Use

Probably the greatest improvement to the MondoKing from older iterations is the new and improved valves. They are located on each of the bottom two corners of the mat and are clearly labeled IN and OUT. They are noticeably larger than the old two-way valve, meaning more air can be moved through them, and since they are one-way, they are easier to use.

The MondoKing can still be blown up by mouth, but the stuff sack doubles as an inflation sack, meaning you can inflate without getting lightheaded. The sack snaps onto the valve, and then you blow lightly into the bag (or even better, catch a breeze) and then roll up the sack to push air inside. We can't quantify that it is three times faster than the old system, as Therm-a-Rest claims, but this system is very easy to use. For the initial inflation, we allowed the mattress to self-inflate for about 20 minutes. Then, using only the pump sack, it took about two and a half minutes to fully inflate.

The deflation valve allows air to move quickly out of the mattress. After that, the foam takes some smashing to roll it small enough to fit in the storage sack. However, the one-way deflation valve does not let air in, meaning it is just a matter of rolling once to get most of the air out and then a second roll to squish everything tight.

Warmth

The MondoKing has an R-value of 7, somewhat lower than the older version, which we are guessing is related to the new ridged foam interior. R-value tells you the insulating power of any given sleeping pad or camping mattress, giving you an idea of how cold of a surface you could comfortably sleep on without that coldness seeping through to your body. To winter camp, it's generally recommended to use a sleeping pad or mattress with an R-value of at least 4.

We camped at 18 degrees Fahrenheit with the MondoKing and had zero complaints. If you are heading off for a sub-arctic adventure, there are a few mats in this test that are rated higher for insulation, but for four-season camping in the lower 48 states, the MondoKing should be plenty toasty. It's also just as important to note that, unlike the cold-temperature rating of a sleeping bag, having a camping mattress with an R-value this high won't make you pour sweat in hot weather. This is a solid four-season camping companion.

Versatility

Based on the overall size and weight of the MondoKing 3D, this isn't the camping pad you would take on a backpacking trip. At 5.27 pounds, you won't want to carry this mattress too far from your car or garage. However, it is worth noting that the XXLarge version that we tested is lighter than the old version while being considerably larger.

While our testers quite adored the large surface area, two of these pads in size XXLarge will not fit in the average two-person tent, which is around 50-55 inches wide. The Large size is 25 inches wide, so two of those should fit. We suggest you check this against your own personal tent width, as tent styles and sizes vary. If you are car camping in full glory, however, you may very well have a much larger tent, in which case, why not go all out for maximum surface area?

Packed Size

When packing the car for a weekend of camping, the MondoKing isn't too large to bring and more than makes up for its size with its comfort. While we wouldn't be stoked to pile seven of them in the back of the van, the space it takes up is comparable to the other highly comfort-rated mattresses in this review.

Value

The MondoKing 3D is on the more expensive side of the self-inflating camping mattresses we tested. Despite being a decent chunk of change to throw down on a camping mattress, we think you'll find the comfort and ease of use to be well worth the dough.

Conclusion