Good call, Pat- Its a Zen-Noh- A chinese Yanmar knockoff. No, it doesn't have a snorkel, no he didn't make it out on his own. I had to whip out the ol' Ford 575 (I'll snap a pic later) that I use for clearing my driveway. The intake didn't quite drown, it did stay running the entire time.
The back story- I was goofing off with the UTLTV at the front of the pond in a muddy area, shooting some video sequences. My buddy had just done some work to his tractor (including new tires) and was taking it for a run. He came over to see what I was doing, and to show off a bit, he backed into the pond a bit, and drove out. I said "that woulda made a great picture!" So he offered to do it again with the camera rolling... LOL...
This time, he found a rut or a little dropoff and just couldn't quite make it out. He said part of the problem was the cooling fan was propellering in the water and robbing a lot of power.
After he got it back, he started pulling corks (on my advice) and found a bit of water in the engine oil, and a ton of water in the differentials and transmission. As you can imagine, all the vents were submerged for about 10 minutes or so.