What are the best things to do in myrtle beach, sc?

Keep in mind a lot of things are closed right now, because it's out of season. I'm going with three other friends (we're all 18) on the 18th and 19th of march (next weekend.) We're going to the ripley's attractions, thats a given. But other than that we're not sure what to do that's exciting, but that doesn't cost so much. We looked at Dixie stampede and Medival times, but they were way too much (50 a person). Anything you enjoyed or have gone too during this month in past years?