Six Flags Hurricane Harbor Chicago

On September 10, 2004, Gurnee officials confirmed plans for a water park opening on Six Flags Great America's existing site.[8][9] Six Flags Great America officially announced the Caribbean-themed water park on September 16, 2004.[10] Plans for the water park included twenty-five water slides, an entrance plaza, and admission separate from the theme park.[11] On January 19, 2005, it was announced admission would be included with a regular ticket.[12] The new water park was expected to compete with others in Wisconsin Dells and the Chicago metropolitan area,[13][14] and would be the biggest expansion in Six Flags Great America history.[15]

Construction on the US$42 million[16] water park began in November of that year, and the water park opened to the public on May 28, 2005.[17][18] The park's centerpiece attraction was the Skull Island interactive playground, which was billed as the largest of its kind, and had 500 gadgets and eight water slides.[19][20] Almost a month following the opening of Hurricane Harbor, a man had a heart attack in Hurricane Bay and died on June 22, 2005.[21] During the water park's first year of operation, it was reported 1.3 million people had attended it, which park officials regarded as a "huge success".[16]

Tornado in 2006

Following the initial opening of Six Flags Hurricane Harbor, a funnel water slide named Tornado was announced on January 14, 2006, at the American Coaster Enthusiasts "No Coaster Con" convention. It would open later in 2006 and be located above the Castaway Creek lazy river.[16][22] The ride opened on Memorial Day weekend in 2006.[23] A few weeks later, a girl was slightly injured and required stitches after she fell off of her tube.[24]

On May 26, 2011, a new roller coaster was planned for the adjacent Six Flags Great America amusement park; it was announced at a zoning board of appeals meeting for the site of Space Shuttle America. The planned roller coaster was Chang, which would have been acquired from the former Six Flags Kentucky Kingdom and was to be located near the park's entrance but the new ride was later canceled.[25][26] Instead, the four-acre (1.6 ha) Riptide Bay area was added to the park, opening on June 3, 2011.[27] Riptide Bay initially included a surf simulator, five water slides, a Caribbean-inspired activity pool, and cabanas.[28][29] In July 2011, a woman suffered injuries on Wahoo Racer and sued the park for negligently operating the attraction. A court upheld an award of US$1.5 million USD in June 2017.[30]

Footers for Tsunami Surge during construction in July 2020

On August 29, 2019, Six Flags Hurricane Harbor announced a new water coaster named Tsunami Surge, which was built by WhiteWater West. Tsunami Surge was billed as the tallest water coaster in the world, and was expected to open for the 2020 season.[31] Ground was broken for Tsunami Surge in January 2020,[32] but the ride did not open due to the park's closure and construction delays during the COVID-19 pandemic.[33][34] On July 20, 2020, the park re-opened with safety protocols regarding COVID-19 in place, and its name was changed to "Six Flags Hurricane Harbor Chicago";[35][36] attractions at Six Flags Great America stayed closed throughout the season.[37]

Beginning on March 22, 2021, Six Flags Hurricane Harbor was separated from Six Flags Great America, and was officially named Six Flags Hurricane Harbor Chicago.[38] A new entry gate for the water park was built in the parking lot, and a pathway between both parks was no longer accessible to the public.[39][37] The change was made to allow guests to choose which park to enter.[40] Previously, the park had charged visitors an additional fee to enter the water park.[37] On May 29, 2021, Tsunami Surge officially opened to the public as the tallest water coaster in the world.[41]