Rainer
Contributor
I live in Cambridge. Your best bet for close and decent diving is Cape Ann. For a list of shore dives there, see the MIT scuba club website (google is your friend). 45 minutes and you have plenty of good options (Matt lists many above). For simply working on skills, I like the Brownstone quarry in CT (it's a two hour drive, though, and the diving itself isn't nearly as good as Cape Ann). Also plenty of good shore dives in RI and ME (1-1.5 hours away). Seriously, do you plan to take public transportation *with* your scuba gear? You've got a car, use it! 
