There's a castle that's been underwater for over 1,700 years - Apparently.
Located off the coast of Scotland, the Castle of St. Michael's Isle, also known as the Chapel of St. Michael, is a 7th-century Pictish castle that was submerged underwater due to coastal erosion. The castle's remains were discovered in the 19th century and excavated, revealing a chapel and a cemetery. Despite being underwater for centuries, the castle's location and age have been verified through archaeological findings and historical records, making it one of the most intriguing examples of a submerged castle.