i'll have to google Marathon.
I've only been as far south as Venice. I love the blue water and white sand. Used to vacation in Jamaica and Mexico often before i got a wife and then the kids.
Now Florida is my best bet clear water and white sand.
I'd love to put in at Charleston and sail down to the keys but that would be one rough and long ride in a Venture 21.
I'm very new to sailing, the thought of the currents coming out of and around all the rivers and ICW's all along the atlantic coast are a bit much for me to want to deal with.