I agree with Elaine. A deep pond with straight sides is the best bet to deter predators. I like the idea of the 'island' in the middle of the pond to act as a shelf for the water plants.
One thing I have never understood, is why we see all these pond designs that show the step like shelves that go to the bottom of the pond. In my mind, that is an open invitation for predators.
Paul's statement that raccoons are going to find their way around any barrier I think is accurate. They are cunning little critters.
