A bill authorizing the Secretary of the Interior to preserve the Marshlands of the Nassau Valley in the State of Florida, to enhance the protection and interpretation of important historic and prehistoric sites in the vicinity of the Nassau, Saint Mary's, and Saint Johns River Valleys, Florida, and for other purposes.

Title I: Fort Caroline National Memorial - Makes the Fort Caroline National Historical Park, Florida, the principal interpretive and administrative center for historic and prehistoric sites in the Nassau, Saint Mary's, and Saint Johns River Valleys. Eliminates the limitation on authorizations.

Title II: Preservation of Nassau Marshland Areas and Protection of Significant Historical Assets - Establishes the Nassau Aquatic Preserve, Florida, which includes specified marshlands, historical land sites, and the Theodore Roosevelt Preserve. Authorizes the Secretary of the Interior to acquire lands within such preserve through donation, purchase, or exchange. Authorizes the Secretary to acquire sites or properties of significant historic interest in northeastern Florida through donation or purchase with donated funds.

Requires the Secretary to manage the Preserve according to applicable Federal, State, and local laws and management programs.

Authorizes appropriations.