In a vacuum seal bag combine 3 cups of water and 1/4 cup of rubbing alcohol. Place in a container upright and freeze. (Seal after you freeze it.) It will not freeze solid, but will create a hard slush (like a gel).
Make up several different sizes use for Ice packs for arms, legs, banged knees, or toss them in your cooler to keep your drinks cold on the way to the beach.