Day 5.133: Is it a beaver, is it a muskrat...?

At Five Rivers the other day, I saw a large animal surface in the middle of the lake and was sure it was a beaver. It wasn't:



Then I saw an animal swimming rapidly underwater with a long rat-like tail out behind it and was sure it was a muskrat. It wasn't:



Three turtles in all - two fighting (again) and one swimming.

This from a week earlier however (thanks for your guesses), was in fact a muskrat, churning up the mud near the side of the lake for reasons unknown:

At least these animals were all alive when I photographed them!