Riverside Park in Newhaven has been deemed to be worth just £1 by East Sussex County Council.
Deputy leader Cllr Keith Glazier decided to sell the site, formerly used for landfill, for £1 to Round Table Entertainments Ltd, the company proposing to build a water park.
The main reason for the decision, made at a community and resources lead member meeting on Tuesday, was 950 new jobs would be created in the Newhaven area if the development goes ahead.
The decision will now be subject to public consultation and reported back in 2013.
Rupert Clubb, Director Economy, Transport and Environment at the County Council said: “The opportunity to redevelop this land will help support the economic regeneration of Newhaven, with the potential of 950 new jobs - something we all want to see.
“We plan to enter into an agreement to sell the land to Round Table Entertainments Ltd but the sale will only go ahead once conditions have been met that protect the interests of local people and council tax payers.”
Conditions include planning consent being granted, Round Table being able to demonstrate the availability of funds for the development to go ahead and a scheme of environmental mitigation works.
If the development fails to happen the County Council will retain ownership of the land.
The meeting heard the 47.2 acres of land next to Lewes Road was a landfill site from 1963 to 1981 but had become an area of open public space with natural vegetation and paths.
This site and land already sold to Round Table is planned to house a hotel and water park leisure development and was an opportunity not to be lost.