Mystic is often invaded by tourists, sure, but pirates? Well, that only happens once a year.

Sunday, buccaneers land at Mystic River Park for the fourth annual Mystic Pirate Invasion organized by the Downtown Mystic Merchants Association. 

Those pirates arrive in style — on the Argia — at noon. Then, the militia gives them a battle royale at Steamboat Wharf. That's just part of the festivities, though. Starting at 11 a.m., kids can participate in a treasure hunt, have their faces painted and see balloons creations whipped up for them at Mystic River Park. Pirate stories are told at 1 p.m. at Bank Square Books, and a haunted history pirate tour leaves at 5 p.m. from Mystic River Park.

For more information, visit facebook.com/mysticpirates.