The principal mountain range, the Cordillera Central, begins at the extreme eastern point of the island, traverses the center of the Republic, crosses into Haitian territory and sinks into the sea at Mole St. Nicolas to reappear in Cuba, on the other side of the Windward Passage. It constitutes a part of the great ridge which forms the backbone of all the islands bounding the Caribbean Sea on the north. In the eastern part of Santo Domingo the range consists merely of a chain of high hills which rarely reach an altitude of more than 900 feet, but in the center and west of the Republic it assumes much greater magnitude, sending out branches which are important mountain chains in themselves, and several of its peaks are over 6000 feet in height. The highest point in the island and in the West Indies is Mt. Tina, with an altitude of 10,300 feet, a magnificent outpost of that branch of the central range which traverses the south-central portion of the Republic. The next highest point, is Yaque Peak, 9700 feet high, nearly at the center of the island. The dense jungle covering the rugged slopes of these giants has so far baffled the few attempts at exploration of their summits. To the west of Yaque Peak is Mt. Cucurucho, 7400 feet high, and to the northwest Mt. Entre los Rios, 8000 feet and Mt. Gallo, 8200 feet in height. It must be remembered that in the absence of any careful measurements, the altitudes given are mere approximations. The Cordillera Central is peculiar in its numerous branches which are often more intricate in their ramifications and comprise loftier peaks than the parent range. The most important of these branches are those which extend from Mt. Banilejo to the southern coast, and fill the district between San Cristobal and Azua with a jumble of mountains. Besides Mt. Tina, already mentioned, their principal peaks are Mt. Rio Grande, 6900 feet, overlooking the beautiful Constanza Valley, and Mt. Valdesia, 5900 feet high. One of the best defined ranges on the south is the Sierra del Agua, which runs south from the Central Cordillera to the San Juan River. The branches on the north are even more numerous and cover a greater area. Among them special reference may be made to the Sierra Zamba, which runs parallel to the Yaque del Norte River, the Sierra de San Jose de las Matas, the Santiago Range, the Jarabacoa Range and the Cotui Range.