An island has always been my thinking for the best place to reside and Michonne had the same idea early in this season. If they can't climb fences or unlock gates then I don't think they have the capacity to swim or weight themselves down to walk on the bottom of a body of water. An island in a river or lake would gove a source of food and fresh water. I have an island scoped out that has a lodge and one narrow road in or out but I can't tell you all where it is or you might show up and cause me to go all Rick Grimes on you.