Are your kids a little older? Tweens (and older yet!) like this size of reusable water balloons; they hold more water, go farther and SPLAT wider!
And these also make wonderful bath-time scrubbies for any age, getting softer with each use! Toss them in the laundry when they get dirty.

These excellent toys are also a great craft fair item, bagged and sold in groups with an explanation of what they are (& are NOT) - many older folks look at them and wonder how you get the balloon filled... Explanations of why latex balloons are hard to pick up and pollute the environment can cause eyes to glaze over; I tell them to give a bucket of water and a couple or three 'balloons' to each child and stand back. The kidlets know what to do!