Stop by the Chicago River on a summer day, and you'll find plenty of kayakers, architectural cruise boats, and people snapping photos and making memories. But swimming, let alone organized swimming in the Main Branch of the Chicago River downtown is not a common sight.

As many as 500 swimmers are expected to dive into the Chicago River next month as part of a fundraiser for ALS research and youth educational programs.

The Chicago River Swim (CRS) is officially coming back in September and will be held on Sunday, Sept. 21, from 7 to 10 a.m. The City of Chicago officially approved the event, marking the first open water swim in the Chicago River in 98 years.