Come on in the water's fine!
Judging by the steam coming from his engine and exhaust before he even gets into the water, the temperature appears to be on the lower end of the spectrum. Clearly that doesn’t seem to bother this guy as he “jumps” right in. He might consider engaging four-wheel drive before jumping into a mud hole next time.
ATV.com recommends that ATV riders always wear a helmet when behind the bars.