Uh...York? The bridges beneath the Castle and near Belle could be used too. Other than that I can't think of much.

Edit: Actually I just had an idea. We could make it so that the amored panda and turtle mount can swim the seas. The Panda can also get an uplift on land speed while the turtle can get a lift on water speed. It'd still make sense to buy the panda as you said, there is more land than water.