Illinois Treasurer Dan Rutherford put on a wetsuit and dove into the Caribbean Reef exhibit to help clean it.
The 90,000 gallon tank is home to more than 400 tropical reef animals, including sharks, stingrays, eel, a sea turtle and a host of colorful fish.
You might not realize it, but Rutherford is a certified scuba diver.
He said he jumped at the chance to come help the aquarium.
"They offered me the opportunity to come into the tanks, help clean the tanks, draw awareness particularly with the Guinness Book of World Records large picnic attempt trying to be made. Of such things, even we individuals in our own lives can help mother earth," Rutherford said.
His visit was part of the aquarium's Picnic for the Planet celebration. It's part of an attempt to set a world record for the most outdoor picnics in 24 hours across the globe.