In the middle of the Westport River lies Shiprock. Shiprock is a granite island, that understandably looks like a giant oceanliner. Most of the Rock is Class 4 and covered with poision ivy, but there are some contrived moderate bouldering problems that can give you a good work out. I really wouldn't recommend going there unless you are planing on going swimming and happen to have your shoes along with you.
Get in your boat, head up the west branch of the Westport River, look for a big rock that looks like a ship.