Governors Island could be a four minute gondola ride away from Lower Manhattan and Brooklyn if a plan presented yesterday to build an aerial connection between the three points becomes a reality.

The proposal, which would require a litany of approvals and much analysis, includes two dramatic cat’s cradle-style structures designed by the Spanish architect Santiago Calatrava.

The suspension structures, estimated to cost $125 million, would stretch from Lower Manhattan to Governors Island and from Governors Island to Brooklyn. The span could also act as a commuter link between Brooklyn and Lower Manhattan. Mayor Bloomberg and Mr. Calatrava said yesterday they could carry up to 3,000 people an hour in each direction in globe-like gondolas.

The design is one in a series of possible New York projects for Mr. Calatrava. The architect recently created a design for the World Trade Center transit hub and for a building of glass cubes to be built by the South Street Seaport. He is currently the subject of an exhibit at the Metropolitan Museum of Art.

Mr. Bloomberg’s deputy mayor for economic development, Daniel Doctoroff, said the city and state would “set a new standard of imagination and ambition” in redeveloping the island, which has already seen many false starts.

“Everybody seems to agree on one thing: This is an opportunity we will never have again,” Mr. Doctoroff said during a news conference. “That opportunity makes this RFP an RFP like none other,” he added, referring to a request for proposals put out for public bidding yesterday.

Mr. Bloomberg and Governor Pataki have each committed $30 million from the city and state budgets for this fiscal year to the redevelopment, bringing the total commitment to about $120 million. The chairman of the Governors Island Alliance, a coalition of civic groups, Kenneth Fisher, said yesterday in a statement he was concerned about how the state and city are proceeding. “The Island cannot simply be sold to the highest bidder,” Mr. Fisher said.

The group’s executive director, Robert Pirani, called private sector partnerships “essential to the success of the Island and preservation of its historic buildings,” but said “these developers should not be made responsible for deciding how best to provide parks and public programming on the Island.”

The island does come with deed restrictions and the development that ends up there must be financially self-sustaining, but yesterday Mr. Doctoroff indicated that preliminary ideas from private developers ranged from a “major entertainment complex” to a center that will study the “greatest problems of global health.” Yesterday Mr. Bloomberg ruled out only a golf course and a football stadium, but said the possibilities where wide open.

Mr. Doctoroff said deed restrictions preclude permanent residential housing, industrial buildings, and parking beyond what’s need for operations. Mr. Doctoroff said a hotel and other for-profit business were possible.