Mystery Bay

Mystery Bay State Park is a small, 10-acre marine camping park located on Marrowstone Island in Jefferson County, Washington. The park sits on the eastern shore of the island facing the entrance to Oak Bay, providing protected waterfront access on the waters of Puget Sound. Established as a state park in the 1960s, Mystery Bay offers a quiet retreat for beachcombers, kayakers, and campers seeking a peaceful coastal experience. The park's small size creates an intimate atmosphere, with limited development maintaining a natural character. The pebbly beach provides opportunities for tidepooling, shellfish harvesting, and shoreline exploration. The name 'Mystery Bay' reflects the area's secluded, hidden character, tucked away on a relatively remote island accessible only by road through the Quimper Peninsula. The park serves as a base for exploring the scenic waters surrounding Marrowstone Island and nearby Fort Flagler State Park. Its location offers stunning views across the water to the Cascade Mountains and surrounding islands.

Mystery Bay's marine and shoreline habitats support diverse Puget Sound wildlife. Harbor seals frequently haul out on nearby rocks and forage in the bay's productive waters. Sea otters occasionally visit the area. The intertidal zone hosts rich communities including sea stars, anemones, crabs, barnacles, mussels, and various shellfish. Subtidal waters support rockfish, Pacific cod, and salmon during migration periods. Seabirds are abundant, with species including cormorants, gulls, pigeon guillemots, scoters, and various diving ducks. Great blue herons stalk the shallows during low tide. Bald eagles nest on Marrowstone Island and frequently hunt along the shoreline. Shorebirds including killdeer and sandpipers forage in the intertidal zone. The adjacent upland forest provides habitat for black-tailed deer, raccoons, river otters that fish in the bay, and various small mammals. Amphibians including Pacific tree frogs occupy freshwater seeps. The convergence of marine and terrestrial ecosystems creates high biodiversity in this small park.

The park's vegetation reflects typical Puget Sound lowland maritime forest communities. Douglas fir dominates the canopy, with western redcedar, western hemlock, and some bigleaf maple in the forest. The understory includes salal, Oregon grape, evergreen huckleberry, and sword fern, characteristic of western Washington forests. Red alder grows along the shoreline and in disturbed areas, enriching soils through nitrogen fixation. Pacific madrone with its distinctive peeling red bark grows on well-drained slopes. The shoreline transition zone features salt-tolerant grasses and seaside plantain. Beach logs provide habitat for invertebrates and perching sites for birds. Some invasive species including Himalayan blackberry occur in disturbed areas. The forest canopy provides shade and shelter for the small campground. Limited understory clearing has been conducted to maintain campsites and trails. The intertidal zone supports eelgrass beds visible at low tide, providing critical habitat for fish and invertebrates. Kelp and other marine algae grow in subtidal areas. The forest contributes large woody debris to the marine environment, creating habitat complexity.

Marrowstone Island and Mystery Bay are situated within the Puget Lowland, a glacially carved depression between the Olympic Mountains and the Cascade Range. The area's geology reflects extensive glaciation during the Pleistocene epoch, with the Vashon ice sheet covering the region until about 14,000 years ago. As glaciers retreated, they left deposits of glacial till, outwash, and marine sediments that form the island's substrate. The shoreline at Mystery Bay consists of glacial deposits including cobbles, pebbles, and sand derived from the erosion of glacial sediments. Bedrock in the area consists of Tertiary sedimentary rocks, though these are largely obscured by glacial deposits. Post-glacial isostatic rebound and sea level changes have shaped the current shoreline configuration. The protected position in the lee of the Olympic Peninsula reduces wave energy, allowing finer sediments to accumulate. Tidal currents through Oak Bay entrance influence sediment transport and marine habitat. The beach face shows typical Puget Sound characteristics with a gravel berm at high tide transitioning to finer sediments lower in the intertidal zone.

Mystery Bay experiences a moderate maritime climate characteristic of the Puget Sound region, with mild, wet winters and warm, dry summers. The Olympic Mountains to the west create a rain shadow effect, resulting in less precipitation than locations further west. Annual precipitation averages 25-30 inches, significantly less than the Olympic Peninsula's western slopes. Most rain falls between October and April, with summer months typically dry. Winter temperatures rarely drop below freezing, averaging 35-45°F. Summer temperatures are moderate, typically 60-75°F, cooler than inland areas due to marine influence. Fog can occur year-round but is most common in late summer and early autumn. The park's eastern exposure provides some shelter from prevailing westerly weather systems. Winds are generally moderate, though occasional winter storms bring strong winds from the south. The maritime climate supports the mild temperate forest and creates comfortable conditions for water-based recreation much of the year. Tidal ranges average 8-12 feet, exposing extensive intertidal areas during low tides.

The waters around Marrowstone Island and Mystery Bay were traditional territory of Coast Salish peoples, particularly the S'Klallam and Chimacum tribes, who utilized the area's rich marine resources for thousands of years. Shellfish harvesting, fishing, and hunting were central to their subsistence. European and American exploration of Puget Sound began in the late 18th century, with George Vancouver's expedition charting the area in 1792. Settlement of Marrowstone Island occurred in the late 19th century, with homesteaders attracted by timber and agricultural potential. The island's strategic location at the entrance to Port Townsend Bay led to military reservation of the northern end, resulting in Fort Flagler's establishment in 1897. Mystery Bay area remained in private ownership until acquisition for the state park system. The name's origin is uncertain, though it likely reflects the area's secluded character. The park was developed in the 1960s as part of Washington State Parks' expansion. The area has served recreational uses including camping, beachcombing, and boating. Traditional shellfish harvesting continues under state regulations.

Mystery Bay State Park was established in the 1960s as Washington State Parks expanded its system of small marine camping parks around Puget Sound. The 10-acre site was acquired to provide public access to Marrowstone Island's shoreline and create a water-trail campsite for kayakers and small boaters. Initial development included basic camping facilities, restrooms, and a short trail to the beach. The park was designed to maintain a natural character with minimal infrastructure, appealing to visitors seeking a less developed camping experience. Over the decades, the park has seen modest improvements including updated restroom facilities and improved water systems while maintaining its intimate, low-key character. The park became part of the Cascadia Marine Trail, a water trail system spanning 150 miles from Olympia to the San Juan Islands, with designated campsites for kayakers. Management has focused on protecting shoreline ecosystems while providing appropriate public access. The park's small size has limited visitation somewhat, preventing overcrowding. Nearby Fort Flagler State Park's development as a larger recreation area has allowed Mystery Bay to remain relatively quiet. The park continues serving its original purpose as a simple coastal camping retreat.

Mystery Bay State Park's main attraction is its pebbly beach, accessible via a short trail from the campground. The beach offers excellent tidepooling during minus tides, with tide pools revealing marine life including sea stars, anemones, crabs, and various invertebrates. The shoreline is suitable for kayak launching, with calm waters inside the bay ideal for novice paddlers. The beach provides opportunities for shellfish harvesting including clams and oysters (when beds are open and testing shows they are safe). Beachcombing yields interesting shells, beach glass, and driftwood. The park serves as a base for exploring the waters around Marrowstone Island, with nearby Fort Flagler State Park offering additional recreation. Sunset views across the water are spectacular on clear evenings. The small campground itself is nestled in forest, providing a quiet setting. Bird watching is rewarding year-round with both marine and forest species. The park's location makes it a convenient overnight stop for kayakers on the Cascadia Marine Trail. Simple loop walks around the campground allow exploration of the forest environment.

Mystery Bay State Park offers basic facilities suited to its small size and low-key character. The campground has 10 standard campsites suitable for tents and small RVs, though facilities are minimal. Sites include picnic tables and fire rings but no hookups. Vault toilets and potable water are provided. A small parking area serves day users and campers. The park requires a Discover Pass for day use and camping fees for overnight stays. Reservations are recommended during summer months. The park is accessible via Flagler Road on Marrowstone Island, reached from State Route 20 via the Quimper Peninsula and a bridge to Indian Island, then Marrowstone Island. The drive from Port Townsend takes approximately 30 minutes. No stores or services exist on Marrowstone Island; supplies should be obtained in Port Townsend or Port Hadlock. Cell phone coverage is limited. The park operates year-round though winter visitation is light. Maximum stay limits apply during peak season. The park's small size means it fills quickly on summer weekends. Nearby Fort Flagler State Park offers additional amenities if needed.

Washington State Parks manages Mystery Bay with emphasis on protecting its marine shoreline and forest ecosystems while providing appropriate public access. Shoreline management includes protecting eelgrass beds critical for juvenile fish and invertebrates. Park staff and volunteers monitor intertidal health and watch for invasive species. Visitors are educated about proper tidepooling etiquette, including returning rocks to original positions and not disturbing wildlife. Shellfish harvest regulations are enforced to maintain sustainable populations. Water quality monitoring ensures the marine environment remains healthy. The small campground minimizes impacts through its limited size and basic facilities. Invasive plant species are controlled in upland areas to protect native forest communities. The park participates in regional marine monitoring programs. Beach erosion is monitored, though the protected location experiences relatively low wave energy. Driftwood and beach logs are left in place as they provide important habitat. Educational signage informs visitors about marine ecosystems and Leave No Trace principles. The park's inclusion in the Cascadia Marine Trail promotes low-impact, human-powered recreation. Climate change impacts including sea level rise and ocean acidification are areas of concern for long-term shoreline management.