A passenger ship is a transport vessel carrying passengers, baggage and mail. According to the International Convention for the Safety of Life at Sea, a ship carrying more than 12 passengers is a passenger ship, whether or not it is carrying cargo at the same time.

Passenger ships generally have a complete superstructure with various types of cabins and some service cabins; they have strict safety requirements for life-saving, fire prevention, and anti-sinking; they have high comfort, good sound insulation and shock absorption performance; they have higher speed and power reserves. Passenger ships usually have fixed routes and regular flights. With the development of air transportation, sea passenger ships have turned to coastal and offshore short-distance transportation, mostly engaged in tourism business, and inland river passenger ships are still important passenger transport tools in many countries.

There are mainly the following types of passenger ships:

1. Ocean liner. There are ocean-going passenger ships and coastal passenger and cargo ships. Ocean carriers were developed in the 1840 s, when they were mixed passenger and cargo ships. Later, due to the increase in passenger and cargo traffic, passenger and freight gradually separated, a large ocean-going passenger ship was divided into pure passenger. Ocean liners used to be called "mail ships" because they carried mail at the same time. Large ocean-going passenger ships are generally larger than 10000 gross tons, with a speed of more than 20 knots per hour, and there are many public places on board. After the emergence of long-range jet airliners in the late 1950 s, the customers of ocean-going passenger ships gradually decreased. Due to the high cost of construction and maintenance of large high-speed passenger ships, and the speed is much lower than that of aircraft, which does not meet the needs of modern economy, such ships have been in decline for more than ten years. Coastal passenger and cargo ships are generally less than 6000 gross tons, with a speed of 14 to 18 nautical miles per hour, and a large cargo carrying capacity.

2. Inland passenger ships. A traditional passenger ship sailing on rivers, lakes and seas. Due to the large passenger capacity and frequent docking, small amounts of groceries and mail are usually loaded and unloaded at the floating dock via a gangway. The main structure is relatively thin. If the speed of the flight section is less than 3 meters per second, there is no need for double bottoms. Generally, there are two decks with lower freeboard. Due to the convenience of the flight section, the safety requirements are lower than those of sea-going ships. The superstructure extends forward and backward, extending outward to increase the passenger carrying area. Most are double paddles, double rudders or triple rudders.

3. Passenger cars. Car passenger ship is a kind of coastal passenger ship developed in the early 1960 s. It mainly transports passengers and brings its own cars. Its stay in Hong Kong is very short and efficient. Today, the important short-and medium-distance regular routes and train ferry routes in developed countries are basically using motorized passenger ships. Most motor passenger ships are below the gross tonnage of 4000 and can carry 700 to 1000 people, some of which are cabins and some of which are recreational cabins. The ratio of people to vehicles (vehicle-passenger ratio) is 10% ~ 20%, and the speed is 16~18 nautical miles per hour. The draft is shallow, the ship is wide, and it adopts double oars and single rudder. Fins and side pushing devices are provided. The main engine is a medium-speed diesel engine, and the engine room entrance and exit are placed on the side, which is convenient for the vehicle deck (first floor or second floor) under the upper deck to pass back and forth. Most cars get on and off the boat by opening the front and back doors and passing through the movable bridge of the dock. In recent years, due to the development of tourism, more and more high-speed large-scale automobile passenger ships with a gross tonnage of more than 10000 tons, a passenger-passenger ratio of 33% and a speed of more than 20 nautical miles have been increasing.

4. Tourist boats. Tourist ships are similar to large ocean-going passenger ships, with a general gross tonnage of 2-40000 tons and a capacity of 800-1400 passengers. The engine room is located in the middle of the ship and the speed is 20-24 nautical miles per hour. They cruise or regularly circumnavigate the beautiful seas, engaging in inter-port traffic. Tourist boats should not only meet the requirements of tourists, but also enable tourists to achieve the purpose of recuperation, vacation, cultural entertainment and social activities. Bedrooms and public spaces are also graded, often separated vertically. Bedrooms are arranged at the top to keep quiet, and there are also a variety of public places with open views. The tour boat has a shallow draft, a large endurance, and an anti-roll device to make the voyage as smooth and comfortable as possible.

5. Ro-ro passenger and cargo ships. Ro-ro passenger and cargo ships are new passenger and cargo ships developed on the basis of container transportation and large-scale automobile passenger ships, and are mostly used for coastal medium-range regular routes. The ship type is similar to that of automobiles and passenger ships. It is necessary to add an additional layer on the vehicle deck and bring its own inclined springboard to shorten the ship's arrival time and speed up the ship's turnover with efficient ro-ro ship technology. In the Baltic Sea, such ships mainly carry passengers, cars and rolling goods on wheels.