While the theme park Six Flags Great America is currently closed, Hurricane Harbor at 1 Great America Pkwy in Gurnee, Illinois just opened on July 20. In accordance with Governor Pritzker's reopening guidelines, this comes with many rules to keep in mind when visiting the water park.
The preview phase from now until July 26 is only to members and season pass holders. With the reduced amount of people allowed in the park at this time, it's fairly easy to remain socially distant to others around you. There are stickers on the ground to delegate spacing while waiting in lines for the water rides.