LEELANAU COUNTY, MI -- A Northern Michigan Coast Guard helicopter crew on routine patrol captured some excellent images of the shipwrecks that dot the waters off Sleeping Bear Dunes National Lakeshore.

The Traverse City-based crew posted six photos on Facebook showing the various underwater wreck fragments visible this week through the clear, blue water of Lake Michigan now the winter ice has melted.

The wooden steamer Rising Sun wrecked off Pyramid Point in October 1917. Remains of the wreck are visible in the shallow water.

The shallow wrecks dot the water between Sleeping Bear Point and Leland, according to the Coast Guard. The area is part of the Manitou Passage, an underwater preserve between the dunes and the Manitou islands with numerous 19th-century wrecks and submerged docks from former dune towns.

Wrecks photographed by the aircrew include the Rising Sun, a 133-foot wooden steamer wrecked at the base of Pyramid Point in 1917, and the James McBride, a 121-foot brig that ran aground near Sleeping Bear Point in 1857.

In late March, the park service said the wreck of the Jennie & Annie, a schooner that grounded off Empire in 1872, was visible again on the beach halfway between North and South Bar lakes. The wreck periodically surfaces every few years.

Due to factors like beach erosion, wind and waves and variable lake levels, various wreck fragments make somewhat regular appearances along the dunes shoreline. The wrecks are considered property of the state and cannot legally be disturbed.

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• Diver discovers wreck of Westmoreland off Otter Creek beach

Garret Ellison covers business, government and environment for MLive/The Grand Rapids Press. Email him at gellison@mlive.com or follow on Twitter & Instagram