You are CORRECT!! I am from the Balt/DC area and it was always a pain to circumvent those tunnels! What you need to do is take I-695 (Baltimore Beltway) around Baltimore....but....BE SURE TO GO WEST!!! If you go EAST, you will end up going over the Francis Scott Key Bridge....very HIGH....and very LONG.....and subject to TERRIBLE WINDS!!
Just follow I-695 around until you see the signs for I-95 South...it's about 30-40 miles.