operations like marlene's to remove her thyroid get moved down the priority list. she's been waiting to have this operation for three years. >> presently, i'm not on any medication. you know, so the appointment -- apparently it's on this ship. >> you heard marlene correctly. she said a ship. against the blue jamaican sky, you can't miss it. bright white with large red crosses. this is the usns comfort. it's the largest hospital ship in the world. it shares that title with its sister, the mercy. the twin ships are actually oil tankers turned floating hospitals. each the height of a ten-story building. and the length of three football fields. the comfort is currently on a humanitarian mission around south and central america and the caribbean.