Storage Room and Cannon Deck(aft)

A storage room and a cannon deck are located under the lounge of the Going Merry. This is where the crew keeps all their cargo such as beer barrels, water barrels, rations, and treasure boxes in storage. Any treasure that Nami can't keep in the women's quarters is kept here as well. The room also houses two cannons facing each side of the ship.
The bathroom and the women's quarters can be accessed from here. Some towels can be found next to the bathroom's entrance for when one finishes taking a bath. The hatch going down to the women's quarters has a latch to keep out prying eyes.
The steering shaft that is used to steer the ship can also be seen located above this room.