Best Spill Proof Water Bottle: Hydro Flask 12 oz. Insulated Kids Wide Mouth The Hydro Flask 12 oz. Insulated Kids Wide Mouth ($30) is designed just for the kids. Cold beverages will stay cold up to 24 hours and hot liquids stay hot for up to six. Great for packing lunches! Image Source: amazon.com Hydro Flask 12 oz. Insulated Kids Wide Mouth $30 from amazon.com Buy Now