Start on the deck side, swim down to the lobby. Make your way across the decks into C deck, from here make your way along the deck towards the bow checking out the rows of toilets and all the artifacts.
When you reach Cargo 2 drop down and head through a hatch back into B deck, here is the sign for the ladies toilets and a typewriter among other things. Weave your way back down to the lobby and into A deck.
From here you will swim over and through bathrooms, back up and out through one of the doors onto the deck and head back to the bow.