Mystery Bay is a hook-shaped inlet at the center of Marrowstone Island that enjoys natural protection from winds that can blow from Puget Sound to the east. The bay is a popular spot for anchorage and mooring, and you're bound to see several boats in the bay no matter the season. Situated near the mouth of the bay on the north shore, the 10-acre Mystery Bay State Park is one of the best access points for large and small boats. A large boat ramp, a dock with 30 moorage slips, seven moorage buoys, and a pumpout facility are all available for marine services. While nearby Fort Flagler is also a popular spot for boat launches and mooring, Mystery Bay State Park is more specifically designed for boat traffic. While the beach is pebbly, it also makes a great spot to launch personal watercrafts such as kayaks and stand-up paddleboards. The park also has a few day use facilities as well, such as picnic tables, fire pits, and vault toilets. If you visit on a clear day you'll have beautiful views of the Olympic Mountains peeking up to the southwest.
Due to the extensive Puget Sound, the Washington State Parks + Recreation Commission boasts the most extensive mooring system in the U.S. All buoys and dock moorage slips are based on a first-come, first-served management system with a three consecutive night limit. Permit and payment of moorage fees are required.