Washington Park Arboretum is a 230-acre collection of trees, shrubs, wetlands, and garden paths between Madison Valley and Lake Washington. Managed with the University of Washington Botanic Gardens, it is one of Seattle's best places for a slow walk, especially in spring bloom or autumn colour.
The paths range from easy loops to longer rambles through woodland and marsh. The Japanese Garden, at the south end of the arboretum, has separate admission and is worth adding if you have time.