Food Supply
Submarines have to stay underwater for weeks or even months at a time, so food is an important issue. Fresh food only lasts for a couple of weeks, and then the chefs have to be creative with what dried foods they have on hand. They can still cook great meals, including complex dishes such as lasagna.
Other preservation techniques include storing fresh food in various nooks and crannies, extending their shelf life. Since it gets really cold underwater, perishables can last a little longer than on land.