Grab your towels and flip flops, because we're heading to the beach. Whether you love playing in the sand, or dread getting it off your feet, building a sandcastle is an often underappreciated art form. In today's encore episode, Emily Kwong asks, scientifically, what is the best way to make a sandcastle? What's the right mix of water and sand to create grand staircases and towers? Sedimentologist Matthew Bennett shares his research and insights.