Aside from the Outward Bound facility, Thompson Island has function facilities. We had a work outing there and for it used a field for softball, a volleyball court and had our lunch in this enclosed area that I can best describe as an overgrown rectangular gazebo.
Thompson Island is a location for the Outward Bound program. Since I'm not well-versed in it (or even poorly versed on it!), I'll simply put the website address and a photo here.
Phew! My work's done....!
The only way to get to Thompson Island is by boat. For our outing, we chartered our own little ferry boat. Trip took only about half an hour and is a lovely jaunt on the Boston harbor.