Most cruise ships don’t allow pets but do allow service animals. Check with the specific cruise line on which you are planning to travel about regulations regarding pets.
If traveling with a service animal, contact the cruise line early to avoid any problems. You’ll need to provide food for your service animal while on board, and some ports may have strict regulations about allowing them to leave the ship.
For train travel in the United States and parts of Canada, Amtrak (https://www.amtrak.com/onboard/carry-on-pets.html) allows some pets (cats and dogs up to 20 pounds [9 kg]) on certain routes. Check with Amtrak for details.
In Europe, many trains allow pets, but rules vary by country. Some countries require dogs to be on a leash, while others require carriers. Check with the rail carrier in the specific country where you plan to travel regarding regulations about pets.
As with air travel, when traveling with a pet on a ship or train, ensure your pet has proper identification, and carry copies of medical records and health certificates if needed.