Chances are that if you are in the Florida Keys, you will  eventually  enter Florida Keys National Marine Sanctuary. The sanctuary protects   the waters surrounding the Keys, extending from south of Miami westward  to  encompass the Dry Tortugas, excluding Dry Tortugas National Park.  And with a shoreward  boundary that starts at the mean high-water mark,  once you set foot in Keys  waters, you are in the sanctuary.
 Florida Keys National Marine Sanctuary is a special place,  with  spectacular and unique resources such as coral reefs, shipwrecks,  seagrass  beds, and fisheries that are the source of commercial and  recreational  activities like diving, fishing, and boating. The   sanctuary is in place to protect these resources, but their ultimate  protection  hinges on you and other visitors following sanctuary rules  and taking simple steps to be a good,  thoughtful steward of the  environment.