“Green Lake” is the name of the neighborhood, and the park, and the lake.
There is no Wikipedia article for the park itself, but the article for the lake has a section about the park.
Green Lake Park (Seattle) (historylink.org)Green Lake Park is a 323-acre park located in north Seattle, adjacent to Woodland Park. Famed landscape architect John Charles Olmsted included a boulevard around Green Lake in his 1903 plan for Seattle’s park and boulevard system. The Board of Park Commissioners acquired the lake and surrounding land by 1908 and hired Olmsted to create plans for the park in 1908 and 1910. Over the years, the park evolved from a boulevard, to a rustic lakeshore park, to a more formalized park with numerous annual events held on the lake, to a park with fewer water-based events, but a highly used pathway circumnavigating the lake. It is one of the most popular parks in the state.