Yeah, they waterproff the hell out of these things. The radiators are relocated, those tubes above the handle bars are air intake for the engine, one intake for the CVT and one exhaust for the CVT. The engine air filter housings are then sealed with silicone. Most electrical connections are already pretty waterproof but a healthy dollop of dielectric grease keeps out the rest. As long as the engine keeps running and the air intakes stay above water, the exhaust won't allow water back that way.
There is no doubt doing this kind of deep water fording is tough on the machines and likely will reduce their service life, but the guys & girls who run them love to modify, repair, replace, upgrade and generally play with their toys.