What happens if a sandbox gets wet?

Could you please explain to me what the consequences would be if a sandbox became damp or wet? Would the sand become unusable? Would it cause any damage to the sandbox itself or its surroundings? Would it be safe for children to play in a wet sandbox? Also, is there a way to prevent a sandbox from getting wet or to quickly dry it out if it does become damp? I'm curious about these details as I'm considering installing a sandbox in my backyard but live in an area with frequent rainfall. Thank you for your assistance.