located_in_the_administrative_territorial_entity florida state road 906
Biscayne ___MASK43___ is a U . S . ___MASK43___ located in southern ___MASK15___ , south of Miami . The park preserves Biscayne Bay and its offshore barrier reefs . Ninety - five percent of the park is water , and the shore of the bay is the location of an extensive mangrove forest . The park covers and includes Elliott Key , the park ' s largest island and first of the true ___MASK15___ Keys , formed from fossilized coral reef . The islands farther north in the park are transitional islands of coral and sand . The offshore portion of the park includes the northernmost region of the ___MASK15___ Reef , one of the largest coral reefs in the world . Elliott Key is the northernmost ___MASK99___ the true ___MASK15___ Keys ( those ' keys ' which are ancient coral reefs lifted above the present sea level ), and the largest key north ___MASK99___ Key Largo . It is located entirely within Biscayne National Park , in Miami - Dade County , ___MASK15___ , east ___MASK99___ Homestead , ___MASK15___ . It is bordered by the Atlantic Ocean to the east , Biscayne Bay to the west , Sands Key ( across Sands Cut ) to the north and Old Rhodes Key ( across Caesar Creek ) to the south . Adams Key is just west ___MASK99___ the southern end ___MASK99___ Elliott Key . Elliott Key is about seven miles ( 11 km ) long . Its maximum width is about near the north end and its average width is less than . The higher elevations on the island range from 6 to above sea level and occur generally along an unimproved road that runs longitudinally through the center ___MASK99___ the island . The average elevation is about above sea level . The key is accessible only by boat . Elliot Key has a National Park Service campground , but is otherwise uninhabited . State ___MASK48___ 906 was a state highway that existed from the 1945 renumbering until the 1980s . It began at the eastern end ___MASK99___ the intersection between modern day SR 997 and SR 9336 and ended at Biscayne National Park . The westernmost two blocks ___MASK99___ SR 906 are now the easternmost two blocks ___MASK99___ SR 9336 . ___MASK15___ ( Spanish for " land of flowers ") is a state located in the southeastern region of the United States . It is bordered to the west by the Gulf of Mexico , to the north by Alabama and Georgia , to the east by the Atlantic Ocean , and to the south by the Straits of ___MASK15___ and Cuba . ___MASK15___ is the 22nd most extensive , the 3rd most populous , and the 8th most densely populated of the U . S . states . Jacksonville is the most populous municipality in the state and is the largest city by area in the contiguous United States . The Miami metropolitan area is ___MASK15___ ' s most populous urban area . The city of Tallahassee is the state capital . Corals are marine invertebrates in the class Anthozoa ___MASK99___ phylum Cnidaria . They typically live in compact colonies ___MASK99___ many identical individual polyps . The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton . A state highway , state ___MASK48___ , or state route ( and the equivalent provincial highway , provincial ___MASK48___ , or provincial route ) is usually either a ___MASK48___ " numbered " by the state or province , falling below numbered national highways in the hierarchy ( route numbers are used to aid navigation , and may or may not indicate ownership or maintenance ); or a ___MASK48___ " maintained " by the state or province , including both nationally numbered highways and un - numbered state highways . Depending on the state , state highway may be used for one meaning and state ___MASK48___ or state route for the other . Mangroves are shrubs or small trees that grow in coastal saline or brackish water . The term is also used for tropical coastal vegetation consisting ___MASK99___ such species . Mangroves occur worldwide in the tropics and subtropics , mainly between latitudes ° N and ° S . The total mangrove forest area ___MASK99___ the world in 2000 was , spanning 118 countries and territories . The ___MASK15___ Reef ( also known as the Great ___MASK15___ Reef , ___MASK15___ reefs , ___MASK15___ Reef Tract and ___MASK15___ Keys Reef Tract ) is the only living coral barrier reef in the continental United States . It is the third largest coral barrier reef system in the world ( after the Great Barrier Reef and Belize Barrier Reef ). It lies a few miles seaward of the ___MASK15___ Keys , is about 4 miles ( 6 to 7 km ) wide and extends ( along the 20 meter depth contour ) from Fowey Rocks just east of Soldier Key to just south of the Marquesas Keys . The barrier reef tract forms a great arc , concentric with the ___MASK15___ Keys , with the northern end , in Biscayne National Park , oriented north - south and the western end , south of the Marquesas Keys , oriented east - west . The rest of the reef outside Biscayne National Park lies within John Pennekamp Coral Reef State Park and the ___MASK15___ Keys National Marine Sanctuary . Isolated coral patch reefs occur northward from Biscayne National Park as far as Stuart , in Martin County . Coral reefs are also found in Dry Tortugas National Park west of the Marquesas Keys . There are more than 6 , 000 individual reefs in the system . The reefs are 5 , 000 to 7 , 000 years old , having developed since sea levels rose following the Wisconsinan glaciation . Biscayne Bay (" Bahía Vizcaína " in Spanish ) is a lagoon that is approximately long and up to wide located on the Atlantic coast ___MASK99___ South ___MASK15___ , United States . It is usually divided for purposes ___MASK99___ discussion and analysis into three parts : North Bay , Central Bay , and South Bay . Its area is . The drainage basin covers . The ___MASK15___ Keys are a coral cay archipelago located off the southern coast of ___MASK15___ , forming the southernmost portion of the continental United States . They begin at the southeastern coast of the ___MASK15___ peninsula , about south of Miami , and extend in a gentle arc south - southwest and then westward to Key West , the westernmost of the inhabited islands , and on to the uninhabited Dry Tortugas . The islands lie along the ___MASK15___ Straits , dividing the Atlantic Ocean to the east from the Gulf of Mexico to the northwest , and defining one edge of ___MASK15___ Bay . At the nearest point , the southern part of Key West is just from Cuba . The ___MASK15___ Keys are between about 23 . 5 and 25 . 5 degrees North latitude .