There is a couple of ways to get to the MV by ferry, but if you want to bring a vehicle there is only one way.
http://www.steamshipauthority.com. If you are going to bring a car, I would recommend booking a reservation as early as possible. You pick up the ferry in Woods Hole which is part of Falmouth MA.
If you don't bring a vehicle, there are other options. From New Bedford MA:
http://www.nefastferry.com/
Here is another walk on ferry from Falmouth.
Http://www.islandqueen.com