Thursday is the first day of free admission if you're an Illinois resident.
It's all part of a new series at Shedd called "Night Dives."
You can check out beluga whales, penguins and sea lions through the rest of the month on Tuesday and Thursday nights, which are August 10, 15, 17, 22, 24, 29, 31.
Residents can receive free admission from 5-9 p.m., with the last entry at 7 p.m.
Tickets must be reserved in advance. For more information, visit the Shed Aquarium's website.