Thompson Island was settled as early as 1626 by a Scotsman, David Thompson, who set up a trading post to do business with the Neponset Indians. Today this island is privately owned and inhabited by Thompson Island Outward Bound, a nonprofit organization that develops fun and challenging physical adventures, especially for training and developing leadership skills. As such, the public can explore its 200-plus acres only on Sunday, when it’s wonderful for walking, fishing and birding. A dedicated ferry leaves from EDIC Pier in the Seaport District; see the website for details.