EDIT - I just noticed it's beyond FL territorial waters. Have to check Fed regs.
Could it be this:
Florida Historical Resources Act
Florida's antiquities law (Chapter 267, Florida Statutes), and administrative rules (Chapters 1A-31 and 1A-32) govern the use of publicly-owned archaeological and historical resources located on state property, both on land and in the water. Administered by the Florida Division of Historical resources, the law establishes programs and policies to encourage preservation of historic resources for the public benefit. State-owned underwater resources are those that are located on the bottom of navigable rivers, streams, lakes, bays, and offshore (in the Gulf of Mexico out to 10 miles, and in the Atlantic out to 3 miles).
Major goals of Florida's historic preservation program are to identify, register, protect, and preserve significant historical resources which belong to the public. Divers are encouraged to participate in the identification, recording, and reporting of underwater sites in order to preserve them. However, disturbing or digging of publicly-owned sites is illegal unless permission is obtained in advance from the Division of Historical Resources. Recovery of isolated finds and happenstance discoveries by divers is permissible, but intentional excavation of underwater sites without written authorization is considered a third-degree felony. Its best to record and report what you find, and seek help to proceed with further investigation.
http://www.flsenate.gov/Statutes/index.cfm?App_mode=Display_Statute&URL=Ch0267/SEC13.HTM
267.13 Prohibited practices; penalties.--
(1)(a) Any person who by means other than excavation either conducts archaeological field investigations on, or removes or attempts to remove, or defaces, destroys, or otherwise alters any archaeological site or specimen located upon, any land owned or controlled by the state or within the boundaries of a designated state archaeological landmark or landmark zone, except in the course of activities pursued under the authority of a permit or under procedures relating to accredited institutions granted by the division, commits a misdemeanor of the first degree, punishable as provided in s. 775.082 or s. 775.083, and, in addition, shall forfeit to the state all specimens, objects, and materials collected, together with all photographs and records relating to such material.
(b) Any person who by means of excavation either conducts archaeological field investigations on, or removes or attempts to remove, or defaces, destroys, or otherwise alters any archaeological site or specimen located upon, any land owned or controlled by the state or within the boundaries of a designated state archaeological landmark or landmark zone, except in the course of activities pursued under the authority of a permit or under procedures relating to accredited institutions granted by the division, commits a felony of the third degree, punishable as provided in s. 775.082, s. 775.083, or s. 775.084, and any vehicle or equipment of any person used in connection with the violation is subject to forfeiture to the state if it is determined by any court of law that the vehicle or equipment was involved in the violation. Such person shall forfeit to the state all specimens, objects, and materials collected or excavated, together with all photographs and records relating to such material. The court may also order the defendant to make restitution to the state for the archaeological or commercial value and cost of restoration and repair as defined in subsection (4).
(c) Any person who offers for sale or exchange any object with knowledge that it has previously been collected or excavated in violation of any of the terms of ss. 267.11-267.14, or who procures, counsels, solicits, or employs any other person to violate any prohibition contained in ss. 267.11-267.14 or to sell, purchase, exchange, transport, receive, or offer to sell, purchase, or exchange any archaeological resource excavated or removed from any land owned or controlled by the state or within the boundaries of a designated state archaeological landmark or landmark zone, except with the express consent of the division, commits a felony of the third degree, punishable as provided in s. 775.082, s. 775.083, or s. 775.084, and any vehicle or equipment of any person used in connection with the violation is subject to forfeiture to the state if it is determined by any court of law that such vehicle or equipment was involved in the violation. All specimens, objects, and material collected or excavated, together with all photographs and records relating to such material, shall be forfeited to the state. The court may also order the defendant to make restitution to the state for the archaeological or commercial value and cost of restoration and repair as defined in subsection (4).
(2)(a) The division may institute an administrative proceeding to impose an administrative fine of not more than $500 a day on any person or business organization that, without written permission of the division, explores for, salvages, or excavates treasure trove, artifacts, sunken or abandoned ships, or other objects having historical or archaeological value located on state-owned or state-controlled lands, including state sovereignty submerged lands.
