The ultimate waterproof bag for the beach must feature durable, water-resistant materials with welded seams and waterproof zippers for maximum protection. It should have ample storage capacity for towels, sunscreen, and other essentials, with multiple compartments for organization. Adjustable and comfortable straps ensure easy carrying, while additional features like insulated compartments for drinks and external pockets for quick access to items enhance functionality. A vibrant design adds style and visibility.