Are resin deck boxes actually waterproof?

Most resin deck boxes in this category are marketed as weather- and UV-resistant rather than fully submersible-waterproof. Verified-purchase reviewers across these listings generally report that contents stay dry in rain, but seams and lids can let in moisture in heavy storms or if the box is left on an uneven surface. If you're storing cushions, a box with a tight-fitting overlapping lid is the safer bet.