The aquatic complex at the Palm Beach Gardens Recreation Center has a splash playground and splash pad informally known as Burns Road Sprinkler Park. Here kids can climb a play structure while water shoots up at them, rain splashes down on them, and buckets empty loads of water on their heads! It's a ton of fun! Shallow water surrounds the playground.

For tamer fun for the wee kids, there's a splash pad with smaller buckets that fall on you, warm water (heated by the cement) that shoots up in fountains, an elephant sprayer you can spin around, and a palm tree that spurts water. Young kids can spend hours here. Little kids love to start the water with the hand-activated sensor- they are in control!
There are plenty of shaded comfortable chairs for the lazier grown-ups!
On the other side of the complex is a large swimming pool and some water slides. The slides aren't fun- they are small, and elbow-crunchers. Also the lifeguards here are complete maniacs and won't let anyone have any fun. A line of kids waits to try aquaclimb, a climbing wall that looks fun because when you fall you land in the water!
Bring plenty of sunscreen, hats for the kids, and sunglasses- it's very bright and burny. See hours open below.
Outside the aquatic center is lovely Gardens Playground with a ton of climbing structures, a water mister, sandpit, a rope climber, and swings, partially under the shade of huge trees. 
Nearby check out Gardens Mall, where you can cool down indoors, or Downtown at the Gardens, a super fun outdoor mall with a train, carousel, live music, whole foods store, and sidewalk cafes.

Directions

The Palm Beach Gardens Aquatic Center is located at 4404 Burns Rd, Palm Beach Gardens FL 33410, call (561) 630-1100.
Exit Highway 95 at PGA Boulevard and head inland. Turn left on Military Trail and then left on Burns Rd. Turn right into the parking lot.
Cost to enter is $10 each, $3 for city residents. If you come after 3pm, it's only $6, which works great because it's less crowded and you get less sunburned.
Open 10-noon on Tues, 3-5 on Thurs, and 11-5 on Saturday (March 14, 2015 to June 7, 2015). Open 11-5 on Sundays starting May 24, 2015. 
Open 10-5 daily in the summer (June 8, 2015 to mid-August). In fall (late Aug - end of Sept), open Mon/Wed 10-noon, Tues/Thurs 3-5, and Sat 11-5. From Oct 1 to the mid-March the Splash Park is closed and only the pool is open for lap swims. Confirm the hours on their website.

Click on map for interactive view