Perhaps you meant the largest ship to sail at the time.
The Titanic was 882 feet 9 inches (269.06 m) long. The Seawise Giant, an oil tanker, was almost twice as long as the Titanic (1,504.1 ft or 458.46 m). The Oasis class cruise ships from Royal Caribbean are 1,181 feet long. The Queen Mary II is 1,132 feet long.