Fallout 3 Secret 3

When you cross the bridge to the entrance to rivet city, before you enter, chuck a left and jump down onto the platform below. In a large hidey place to the right, there is an ammunition box and a first aid kit. Then if you continue up the steps, it takes you up to the top deck, where a baseball diamond, (complete with bases, bat, and a ball) straight in front of you. When your ready to leave, next to the stairs is the control tower. There might be some other boxes and things on the top of the ship, as i haven't had much time to look.