No one on the planet will feel sorry for you if you are stuck in New York waiting for your cruise to depart. First of all, you are one of the rare people who is afforded a vacation. Secondly, New York is a city that doesn't even know the word "boredom."
The main problem you have if you find yourself with time to spare around Manhattan or Brooklyn's Cruise Port Terminals is narrowing down the choices. Should you go into the city from Manhattan's Port and wander around Times Square, trying to respect the daily limit on your credit card? Should you try to meet a Rockette at Radio City Music Hall? Or from Brooklyn, should you do as the locals do and get some of the best Latin American food truck eats in town at Red Hook Ball Fields?
You may feel like there is nothing around the docked cruises, but you would be wrong. You can see some of New York's top attractions, whether you gaze at the Statue of Liberty from the cruise terminal itself or go to nearby Louis Valentino Jr. Park & Pier to catch a better glimpse. The world - including New York - is your oyster.