The Secretary of the Interior is authorized to transfer to the State of Florida by quitclaim deed the land, water, and interests therein, previously acquired by the United States of America for Everglades National Park and not included within such park by section 410i of this title, such transfer to be in exchange for the conveyance by the State of Florida to the United States of all land, water, and interests therein, owned by the State within the boundary of the park as described in section 410i of this title: Provided, That exclusion of any land, water, and interests therein from the park boundary pursuant to section 410i of this title shall be dependent upon the contemporaneous conveyance by the State to the United States of all land, water, and interests therein, owned by the State within the park boundary described in section 410i of this title, including land, water, and interests therein, heretofore conveyed to the State, for transfer to the United States for inclusion in Everglades National Park. The effectuation of the transfer provided for in this section shall be a condition precedent to the acquisition by the Secretary of any land, water, or interests therein held in private ownership within the boundaries set forth in section 410i of this title and outside the area designated in sections 410e to 410h of this title, except as such acquisition is by donation.