Ocean liners are traditional passenger ships. An ocean liner typically has 1,500 to 2,000 seats for passengers and hasfacilities of saloons, swimming pools, and sports halls. Prior to advent of airliners, they were the primary mode of intercontinental travel. Nowadays, just a few ocean liners are in operation, their place has been taken by ferries. Some of the famous and most luxurious ocean liners of the past are the Titanic, Olympic, and Queen Elizabeth. The largest ocean liner today is RMS Queen Mary .