Take the kids to explore at the Children's Museum of South Carolina in Myrtle Beach. This interactive Museum offers a massive variety of interactive exhibits for children from the age of ten and under. With exhibits like "Bubble Mania," "Fossil hunt," and "It's Electric" among many more this can a perfect spot for a break from the sun, or a rainy occasion. The museum also hosts birthday parties.
See cmsckids.org for more info on times and directions.