Creative date ideas in the Outer Banks, NC?

I’m heading to Duck in NC tomorrow with a girl I’ve been dating for about 2 months or so. We’re staying in a huge beach-house with my best friend, his family (parents, in-laws, several kids, etc.), and a few other couples our age (there’s going to be like 15+ people there).

I was hoping to sneak off at least once or twice during the week to do something fun and one-on-one with my girlfriend (she’s being a great sport agreeing to be surrounded by my friends for almost a week, after-all). Any ideas for something not too expensive that is creative and fun? Obviously I plan on walks on the beach and the usual, but perhaps you guys can think of some clever suggestions.