The English Channel

From Wikipedia

At the time it was built, it was the heaviest self-propelled ship of any kind. With a laden draft of 24.6 m (81 ft) and a length of 458.45 m (1,504.1 ft), the ship was incapable of navigating the English Channel,[6] the Suez Canal or the Panama Canal. It is generally considered the largest self-propelled ship ever built.[7][8]