Mobile World Congress doesn't kick off for another couple of days, but the 2016 mobile firsts are already rolling in. Cat's new S60 is the latest rugged flagship smartphone to bear the famed machinery brand, and it adds a pair of unique features: a Flir thermal imaging camera and the first waterproof rating to a depth of 5 meters for up to an hour.

What Cat has done is essentially absorb Flir's standalone thermal camera into the body of the phone. The S60 uses the same sensor and performs the same functions: it produces a live thermal image, measures surface temperatures, and can record both stills and video. The resolution is limited to VGA (640 x 480), which hints toward the fact that it's intended to primarily serve immediate and practical purposes. Cat's examples include search and rescue missions, where bodies might be obscured by smoke or foliage, and police checking tyre temperatures to verify claims. Electricians and farmers also present a substantial overlap between the people likely to be interested in owning a rugged smartphone and having the potential to benefit from thermal imaging.

As serious and niche as the Cat S60 may be, the novelty of its thermal camera lends it a newfound measure of mainstream appeal. I tried out a prototype S60 in London this week, and I was quickly overcome by the desire to take it home and scan everything in my house. Exactly how cold are those drafty corners? Does my zebra plushie actually have a heart? Formula 1 engineers use thermal imaging to help them optimize the power systems of the world's most advanced vehicles and there's now a phone that can do the same at the tap of a button. That's special.

What isn't special about the S60? Pretty much everything else. This Android Marshmallow smartphone runs on Qualcomm's Snapdragon 617 processor, includes LTE support, 3GB of RAM, and 32GB of expandable storage, and comes with a 13-megapixel rear and 5-megapixel front-facing camera. If you close off the microphone and earpiece openings using the two yellow notches on its front, the S60 can be taken down to a depth of 5 meters — otherwise its waterproofing is limited to 2 meters — though that doesn't seem like a huge advantage over the typical 1.5-meter rating for waterproof phones. The battery weighs in at a generous 3,800mAh, however the 4.7-inch display only offers an unsatisfying 720p resolution. At least it's bright, reaching a peak brightness in excess of 500 nits, and it supports input with both wet and gloved fingers.

The Gorilla Glass 4 protection up front has been appropriately ramped up for the S60: it's 1mm thick, more than double the typical 0.4mm layer. The surrounding frame is made out of aluminum and the rear is built out of a toughened plastic composite, which only looks like carbon fiber. Bullitt, the company manufacturing this phone under the Cat brand, says it drop-tests the phone from a height of 1.8 meters 26 times — to make sure that every face and corner can withstand crashing against concrete without injuring the internals. So the S60 is no less rugged than any Cat phone that's come before, but now it adds thermal imaging to its list of core capabilities.

The Cat S60 goes on sale at the end of May at a price of $599 / €649. Judged on the core specs alone, that's obviously a high price to pay, but when you consider that Flir's thermal imaging dongle for the iPhone costs $249 just by itself, having it integrated into a supremely rugged phone might just prove its value for some people.