The USS New Jersey, one of the great Iowa Class Battleships, was reactivated in the late 1960s to serve during the height of the Vietnam War. Her forward 40mm guns were removed during a very light and expedited refit before deploying. These now empty "gun tubs" were then sealed and piped, painted blue and made into swimming pools.

The USS New Jersey only served for a couple of years (1968-1969) after being pulled out of retirement and was the only Iowa Class Battleship to have served during the Vietnam War. When the Iowas were re-activated and deeply refitted during the early 1980s to help fulfill , the swimming pools were removed. To my knowledge, the USS New Jersey remains the only US Navy surface combatant to go to war with such a luxury. You can see rare photos of these swimming pools in use

The USS New Jersey, the most decorated of all the Iowa class battleships, is now a museum ship located in Camden, New Jersey.