I wanted to track the event so I wore the watch. I wrapped it a couple times with common kitchen clear wrap and taped it on the band with electrical tape (no I did not take a pic of it... whoops). I started an "other" workout and started the event which included several crawls through mud and water, climbing and jumping over various structures, and lots of sweat and dirt. The Watch did fine and is working normal after the event, but unfortunately the battery died on me after about 5 or 6 hours into the event and none of the workout tracking recorded. I was hoping it would have at least saved up until the battery died and I could access that info after charging. Oh well. But the Watch clearly can take some punishment which is good. Here is a video of the event straight from the Tough Mudder folks to get a sense of what the Watch made it through:
Tough Mudder Tahoe 2015
Tough Mudder Tahoe 2015