The castle itself was built right up against a lake. The lake is now allowed in to a portion of the castle that has sunk into the earth. It's an easy place for fresh water and fish, a wealth of opportunity easily available for the cats. It's very convenient, although in leaf-bare the edges of the lake freeze over, and the sunken castle becomes dangerous to traverse.
A cat who is a skilled summer could possibly, in late new-leaf or green-leaf, swim down the sunken castle and see if anything valuable is there, but proper explanation would require some method to hold their breath for extended periods of time.
The nearest waterfall to the castle, it also happens to fall into an estaury. The estaury has a wealth of crustaceans and insects, and is an easy place to find ducks in new-leaf and green-leaf. While it takes time to travel to - as traversing directly along the cliffs is nearly impossible - it provides an excellent place to camp out for several days.
the lake and falls
Cats don't tend to come to this area. For one thing, it's a difficult journey, requiring either swimming in the sea or climbing up and over and then back down sharp cliffs. It's not a very friendly area. For another, the area feels... wrong. There's something ominous about this place. For the most part, the castle cats don't consider this part of their territory... but sometimes, traversing out this far is necessary, especially in very harsh leaf-bares.
beach stuff
issa grove
special.
The easiest way to and from the castle.