The Hikawa maru was built by the Yokohama Dock company and was launched in 1929. Her first voyage was 5/13/1930 to Seattle, US from Kobe Japan as a cruise ship. Because of her lavish art deco interior she was referred to as the "Queen of the Pacific" and various celebrities of the day were among her passengers. All in all the Hikawa maru crossed the pacific about 254 times. During the war she was repainted and used at as a hospital ship, and used by the US army after.
She was returned to Japan in 1947 and was refitted to once again carry passengers across the Pacific. However the convinience of the airplane cause the Hikawa maru to loose a large amount of travelers and service was terminated in 1960. In 1961 she was permanently berthed at Yokohama and became a floating youth hostel and meusem. The hostel closed in 1973, and the mesuem followed in 2006, despite being declared a "cultural asset" of Yokohama in 2003.
A few years of uncertainty followed, but ultimately Hikawa maru was refurbished and the museum re-opened to the public in the spring of 2008.
I wasn't able to visit the museum in the Hikawa maru because it was being restored during the time I was there, but the outside is very grand so I can only imagine how interesting it is on the inside. Please check her out if you get the chance!
Access: The Hikawa maru is berthed in the harbor along Yamashita Park and can be accessed by taking the Minato Mirai line and getting off at Motomachi Chuka-gai station.