The internal bottom of the storage bench is elevated one inch off the ground and has one inch diameter holes in the base of the box for ventilation. We also include a few 1/4-inch diameter holes just beneath the top lip on the back side wall to allow for cross ventilation. The vent holes don't allow water to get into the box. Or, you can choose your storage bench without ventilation holes at checkout. Our storage benches are made with tongue and groove construction and they are very close to being 100% watertight. But, we prefer to be safe and we recommend you include a piece of plastic at the top of anything you have inside the box so if a few drops of water do get in, they'll just sit on the plastic and nothing gets wet.