Coast Guard Petty Officer 3rd Class Nicholas Greene explains the engineering system aboard the passenger vessel Island Princess to Petty Officer 2nd Class Kate Brinkley in Whittier, Alaska, Aug. 26, 2013. Greene spent two weeks traveling aboard the cruise ship and learning about its operations as part of a ship rider program intended to educate Coast Guard vessel inspectors. (U.S. Coast Guard photo by Petty Officer 1st Class Shawn Eggert)