Orange County Great Park, Public park in Irvine, California

Orange County Great Park occupies 28.8% of the former Marine Corps Air Station El Toro, a base active from 1943 to 1999. The layout, designed by a team led by landscape architect Ken Smith after an international contest, keeps a large section of the old runway as a reminder of the airfield. Its signature structure is the Great Park Balloon, an orange tethered sphere with a ribbed envelope whose open metal gondola holds 25 to 30 people.

The site hosted Marine Corps Air Station El Toro from 1943 until its 1999 closure, recommended by the 1993 Base Realignment and Closure Commission. In 2001 Orange County voters passed Measure W, authorizing a central park and nature preserve; the $1.1 billion project was approved in 2002. A design contest was won by a team led by landscape architect Ken Smith.

The park's name comes from its reuse of MCAS El Toro, and the layout keeps a large section of the original runway as a reminder of the air base. The restored hangar and terraced lawn host special events, while Wild Rivers Water Park, rebuilt here and opened on July 10, 2022, runs a winter lights and market season.

The park is owned by the City of Irvine and run by the non-profit Great Park Corporation, whose board is made up of sitting city council members. The restored hangar and the terraced lawn serve as event venues. The Championship Soccer Stadium and its two FIFA regulation-sized natural-grass pitches sit within the grounds.

The Great Park Balloon, designed and operated by Aerophile SA, opened on July 14, 2007 as the park's first attraction. Its open-sided gondola carries 25 to 30 people at once, and the orange envelope is visible from across the former airfield.