AUGUSTA — Maine officials are encouraging Mainers to explore the outdoors by offering free admission at state parks and historic sites on Father’s Day.

Parks and Lands Director Will Harris says all vehicles with Maine license plates will be let in for free on Sunday, except at Baxter State Park and the Penobscot Narrows Observatory in Prospect.

Additional Photos

In this June 2012 file photo, 3-year-old Casey Chaney, of Scarborough, keeps up with her grandmother Phyllis Allen from Martinsville, Virginia as they help clean up rockweed at Scarborough State Park following a storm. Maine officials are encouraging Mainers to explore the outdoors by offering free admission at state parks and historic sites on Father's Day. John Patriquin / Staff Photographer

In this May 2012 file photo, Ferry Beach State Park Ranger Janet Mangion points out growth in Tupelo Swamp while walking down the boardwalk on Tupelo Trail. Maine officials are encouraging Mainers to explore the outdoors by offering free admission at state parks and historic sites on Father's Day. Shawn Patrick Ouellette / Staff Photographer

Officials say more than 2.6 million people visit Maine state parks and historic sites each year.