A sculpture head has been discovered at the bottom of Lake Nemi, about 31 km (19 miles) south of Rome. It is thought to belong to one of Caligula’s two “floating pleasure” boats.
https://www.ancientpages.com/2023/06/28/roman-marble-head-lake-nemi/
Here is a previous post on the stolen mosaic from one of the pleasure-boats that ended up in New York City.