To amend the National Trails System Act to provide for a study of the Cascadia Marine Trail.

Cascadia Marine Trail Study Act - Amends the National Trails System Act to require the study of the Cascadia Marine Trail in the state of Washington for designation as a national scenic trail. Permits the evaluation of sites of recreational, scenic, or historic significance near the Trail for potential inclusion in the Trail. Provides also for consideration of what activities may be limited by the designation, including existing activities, hunting, boating, or proposed infrastructure improvements.