Cunard Lines, which is owned by Carnival Cruises uses their docks in Brooklyn.
The passenger piers in Manhattan are not really capable of handling the mega cruise ships of today, they were built in the 1950’s to handle ships like the SS
United States and the Queen Mary.
With today’s mega cruise ships, the logistics of moving so many passengers and re-provisioning the ships had caused grid lock around the mid town piers.
Because of this Carnival decided to build new passenger facilities on the Brooklyn waterfront, which is also easier to get to than the mid town piers.
Even Royal Caribbean Cruise lines and its wholly owned Celebrity Cruises abandoned New York City for Bayonne New Jersey for the same reasons. 2 years ago when we took a Celebrity Cruise to Bermuda, we sailed from Bayonne which was nice becasue they had long term parking there. Even driving from Connecticut, it was much easier than fighting the New York traffic if we had sailed from Manhattan.