Plans to create an 11ha landscape in the Queen Elizabeth Olympic Park after the games have finished were submitted to planners last week.
The London Legacy Development Corporation (LDDC)said the South Plaza, to cost around £12m, would form the heart of the southern part of the site and be a "dynamic landscaped public area dedicated to entertainment and activity".
James Corner Field Operations, the landscape architect firm responsible for the High Line linear park in New York, will create mounds, paths and planting overlooked by the ArcelorMittal Orbit sculpture.
Meanwhile, a 12m-wide tree-lined promenade will connect north and south parks and open on to a series of outdoor rooms. These will feature an interactive fountain, a carousel, a space for impromptu performances, a music area and children's play area with climbing wall.
A ribbon of perennial planting will define many of the spaces, including a park hub next to the giant ArcelorMittal Orbit to house a cafe, box office and a rooftop pavilion, said the corporation. It aims to open the park in spring 2014.
This will follow the phased opening of the North Park from 27 July 2013 - one year to the day after the Olympics' opening ceremony, said chairman Daniel Moylan.
He added that the plaza would combine "stunning scenery with an ever-changing event programme".
Landscape architect James Corner, who with Piet Oudolf and Playlink won an international competition to land the job, commented: "The design projects a green, active and playful sequence of spaces for new social uses and interactions."
The South Plaza - urban, activity-driven and like the Southbank Centre in ethos - will contrast with the North Park, which will be rambling and nature-reserve-like, with wetlands and canal paths centred around ecology.
Creation of the Queen Elizabeth Olympic Park will be one of the biggest construction projects in Europe.
The 18-month programme of transformation will lay the foundations for further development across east London over the next 20 years.
The main objectives are to clear temporary venues and bridges, connect the park to the surrounding area with new roads, and complete permanent venues and parklands.