When should I arrive for Cave of the Winds tours on holiday weekends to avoid sellouts?

Arrive 30 minutes before opening because tours sell out before 9 AM on Memorial Day and Fourth of July. The tours are first-come, first-served, and holiday crowds line up at opening (8 or 9 AM). By 10 AM, the next tour might be late afternoon or gone. Don’t bank on noon—set an alarm and bring coffee.