When you enter your stateroom, you must insert your key card in a slot by the door that activates the stateroom lights. You have to remove your key when you leave in order to get back in and the lights won’t stay on when it’s out of the slot. Thus, it’s impossible to leave the lights on and waste electricity.
Plus, it’s a very neat way to keep track of your key card. We really like it and expect to see on other cruise ships in the future.
Photo courtesy of Alan Wilson, Cruise News Daily