US Navy Whidbey Island Class Amphibious Transport Dock.
Commissioned in 1986.
Weighs over 16,000 tons full load, and can carry over 400 US Marines with their equipment and landing craft for them.
Seen here leaving Charleston SC going past Fort Moultrie on Sullivan's Island.
She is being escorted by a local police boat.
She had been in Charleston to help celebrate the Saint Patrick's holiday.
http://uscarriers.net/lsd41history.htm
http://www.navsource.org/archives/10/12/1241.htm
https://www.navysite.de/ships/lsd41.htm