THE NOB!!!

The most wild ride you can get it Maine by far is the Penobscot River in north central Maine. This river is the only river in Maine with multiple class V rapids running daily. Nicknamed "the nob," this river is extremely dangerous and not for the first time rafter. Its features have names like "Fist of God, "Exterminator, and "The Wailing Wall" and they all live up to their names.  Several companies run this river commercially, but it requires special licencing for all the guides so it is a little more expensive but worth the money for the ride.
Here are some awesome pictures of the river and some of its hits.