The signature run in Myrtle Beach is the namesake beach and its festive boardwalk. The beach itself goes on for miles and miles. It’s wide, flat, and very runnable, with fairly consistent packed sand, especially near the water (best around low tide, see chart). The best running is from the boardwalk and heading north. You can go for miles and miles.
Another festive spot for a jog is along the 1.2 mile boardwalk, which runs between 1st Ave. and 14th Ave. This is your classic wooden beach boardwalk, with the requisite open air bars, restaurants, kitschy shops, and amusements. The boardwalk can get crowded, so best to go early. And, a bonus for those hot South Carolina days: the boardwalk is lit at night.