General:
* Vessel
* Craft
* Boat
* Watercraft
* Seafaring vessel
* Nautical vessel
Specific types of ships:
* Sailboat: Yacht, sloop, schooner, ketch, dinghy
* Motorboat: Motor vessel, cruiser, launch, dinghy
* Cargo ship: Freighter, tanker, bulk carrier, container ship
* Passenger ship: Liner, cruise ship, ferry
* Military ship: Warship, destroyer, submarine, aircraft carrier
Figurative:
* Shipment: A package of goods sent by mail or delivery service
* Send: To dispatch or transmit something
* Transport: To move something from one place to another
Informal:
* Boat: A more casual term for a ship
* Barge: A large, flat-bottomed boat
* Tug: A small, powerful boat used for towing
To choose the best synonym, consider the specific type of ship, the context of the sentence, and the level of formality.