Mystery Bay State Park

{{Short description|State park in Washington, United States}}

{{Use mdy dates|date=August 2023}}

{{Infobox protected area

| name = Mystery Bay Marine State Park

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| map = Strait of Juan de Fuca#USA Washington#USA

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| map_size = 280

| map_caption = Location in the state of Washington

| relief = 1

| location = Jefferson, Washington, United States

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| coordinates = {{coord|48|03|32|N|122|41|40|W|display=inline,title}}

| coords_ref = {{cite gnis|1513019|Mystery Bay State Park}}

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| area_acre = 18

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| elevation = {{convert|16|ft|m|abbr=on}}

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| established = 1972

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| operator = Washington State Parks and Recreation Commission

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| website = [http://parks.state.wa.us/550/Mystery-Bay Mystery Bay Marine State Park]

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Mystery Bay State Park is an {{convert|18|acre|adj=on|spell=in}} Washington marine state park on Mystery Bay, a small inlet off Scow Bay/Kilisut Harbor on the western side of Marrowstone Island. The park is located approximately one-half mile north of the Nordland General Store (which also faces Mystery Bay) on Flagler Road (SR 116). Many older wooden sailboats can be swinging at permanent moorage at the park. Park activities include picnicking, shellfish harvesting, fishing, boating, beachcombing, and scuba diving.