Up to 2,000 construction workers building a planned 535-acre theme park could be asked to live on cruise ships on the other side of the Thames.
Plans would see the boats docked in Tilbury, Essex, opposite the London Resort on Swanscombe Marshes in Kent.
The park is currently going through the planning application process and, if approved, work could start in 2022.
"Serious consideration" was being given to the ships idea, the park said.
The London Resort said a lack of hotel rooms and rental accommodation in Essex and Kent meant cruise ships were an option.
It said it had received "several approaches" from ferry companies looking to sell or lease ships.
The site would have two theme parks, a water park, hotels, shopping centres and entertainment venues and it was hoped it could open in 2024.
It was ultimately expected to support 17,000 jobs.
More on the London Resort:
The union Unite has urged the London Resort to discuss the plans with unions before making any decisions.
Unite national officer for construction Jerry Swain said: "On the face of it this looks like an attractive option for workers.
"However, it is essential that the cruise ships don't in reality become an expensive prison.
"At the moment, due to Covid-19, there is a huge surplus of cruise ships but, when that market recovers, it would be immoral to force workers into clapped-out hulks."
He said workers should be able to "leave the ship and visit the local community".
More on Tilbury Docks:
John Kent, opposition Labour member at Thurrock Council in Essex, said there were "all sort of questions which give me cause of concern".
He said the plans did not include where workers would park cars or where they would receive things like medical care.
"The ship will be self-contained, people will be expected to eat on the ship, live on the ship and go back and forward to work. It doesn't bring anything into Tilbury or Thurrock," he said.
Thurrock Council, which is Conservative-controlled, has been asked for comment.
Because of the scale of the project, the final planning decision on building the resort rests with government, although local councils will have an input.