LELAND, Mich. (AP) — The clear blue, post-winter waters of northern Lake Michigan have disclosed some of their hidden history to a U.S. Coast Guard crew, which took a series of photographs of shipwrecks lying on the lake bottom in the waters off the Sleeping Bear Dunes National Lakeshore.

The Grand Rapids Press reports that the Traverse City-based helicopter was a on a routine patrol when the crew spotted the wrecks Friday and got pictures of them.

The shallow waters of the lake off the Leelanau Peninsula near Leland are the site of many 19th and early 20th century shipwrecks. The area is known as the Manitou Passage.

The Coast Guard crew posted six photos of the shipwrecks on its Facebook page. Check them out on the Facebook page or in the gallery below.