There's a 17th-century 'ship castle' off the coast of Scotland - Apparently.
The Vasa Castle, also known as the "Eilean Donan of the Sea," is a 17th-century Scottish "ship castle" that was built on the hull of a ship. Located off the coast of the Isle of Lewis, the castle was constructed in 1680 as a temporary stronghold for the local MacLeod clan. Today, the Vasa Castle is submerged in the Atlantic Ocean and can only be seen at low tide, making it a unique and fascinating example of a ship castle.