For 10 miles W from the Dry Tortugas the bottom is broken and irregular, and consists of coral rock with patches of sand and broken shell. Tortugas Bank, the shoalest part of this area, is 7 miles W of Loggerhead Key and has a least known depth of 37 feet. Depths less than 10 fathoms are found for a distance of 2.5 miles in all directions. Between Tortugas Bank and the Dry Tortugas the depths range from 7¼ to 19 fathoms. Deep-draft vessels should avoid Tortugas Bank, especially in heavy weather.
A 10 M à l'W des Dry Tortugas, le fond est brisé et irrégulier. Il est formé de blocs de corail avec des bandes de sable et de coquillages cassés. Tortugas Bank, est à 7 M à l'W de Loggerhead Key et a une profondeur de moins de 11 m. Les profondeurs de moins de 18 m s'étend sur une distance de 2,5 M dans toutes les directions. Entre Tortugas Bank et Dry Tortugas, les profondeurs moyennes sont entre 13 et 34 m. Les vaisseaux à grand TE doivent éviter Tortugas Bank notamment en cas de temps brumeux.
Loggerhead Key, the other of the two principal keys in the Dry Tortugas, is 2.5 miles W of Garden Key. It have a conical tower, lower half white and upper half black, near the center of Loggerhead Key.
The Dry Tortugas lighthouse, along with the Garden Key lighthouse at Fort Jefferson, were the only lights on the Gulf coast that stayed in full operation throughout the American Civil War. The tower (151 feet above the water) was damaged by a hurricane in October 1873 and plans ...
Garden Key is the site of historic Fort Jefferson National Monument, a hexagonal structure with walls 425 feet long rising from a surrounding moat. In 1846, the US Army began to construct a massive fortification on the tiny island known as Garden Key. Sixteen million bricks were ...
Bird Key Harbor, reached through the narrow channel encircling Garden Key, wich is well marked, is an excellent anchorage. The entrance to Bird Key Harbor is narrow, and care is required to avoid the shoals on either side. The main entrance channel is marked by daybeacons.
The lighthouse on Garden Key arose in 1826. After the 1873 hurricane, a new lighthouse of iron plate was built atop Fort Jefferson, 70 feet High atop the fortress, marking the harbor entrance until its deactivation in 1924.