Down and dirty. That's what you have to do, and what you get near the end. You have to go down and get dirty.
This mud crawl is, as I said, near the end. I don't quite remember correctly but I think it's before the tunnel and then it's uphill, downhill, straightaway and then finish.
I remember slogging through this part of the run last year, just completely wasted. I used my forearms to drag the rest of my body forward. I didn't mind the water so much as I was just thinking about finishing at this point.