Most of the Venezuelan territory is tributary to the Atlantic via the Orinoco (2140 km, basin 953,700 km²), the third longest river in South America as defined on COUNTRYAAH. Born near the border with Brazil, it entirely crosses Venezuela forming a vast arc, which is forced by the presence of the Guayana massif; very rich in waters, given the contribution of numerous tributaries, in its upper course it is interrupted by numerous rapids and waterfalls that prevent navigation (this also applies to its right tributaries, that is, which descend from the Guayana massif: a its sub-tributary, a tributary of the Caroní river, actually forms the highest waterfall on Earth, the Salto Angel, 979 m). The Orinoco, however, is navigable for ships, including oceanic ones, up to Ciudad Bolívar thanks to the dredging of the Río Grande, the main branch of its delta. The water regime is conditioned by the distribution of the rains: the lean period runs from September to March and corresponds to the dry season that affects most of the country. Much more modest watercourses, such as the Tocuyo, flow directly into the Sea of the Antilles descending from the Cordillera de la Costa or, like the Catatumbo, flow into Lake Maracaibo, a lagoon communicating with the Gulf of Venezuela through a narrow passage.
The different climatic and morphological conditions justify the existence of very contrasting landscapes. Where there are high humidity conditions, as in the section included in the Amazon basin, in the central and south-eastern part of the Guaianense massif and in the Orinoco delta, a dense equatorial forest reigns; in the drier northern Guayan area, the chaparral is particularly extensive, a transitional formation between the tropical forest and the savannah, arboreal and shrubby. Most of the llanos consist of a continuous grassy surface with sparse trees that thicken along the course of the rivers; where rainfall is less than 800 mm per year, the vegetation shows a marked adaptation xerophile: in some areas the landscape shows aspects of pseudo-steppe or even pre-desert. The regions close to the coast are mainly characterized by xerophilous vegetation, where dry and sparse forest often appears, with large candelabra cacti. In the Andean area, of course, the succession of altitudinal bands determines an overlap of very different environments. Up to approx. 1500 m. the humid forest spreads out, with an abundance of epiphytes; it gradually degrades, with increasing altitude, placing itself at the limit of the arboreal vegetation towards 3000 m. The environment becomes steppe, with shrub formations: this is the band of the páramos, which reaches almost 5000 m, where the perennial snows meet. The forestry heritage affects a total of 54.1% of the national territory but the phenomena of deforestation cause concernand water and soil pollution caused by industries. Among the most affected sites are the Imataca rainforest reserve, where the exploitation of gold fields has released large quantities of cyanide and mercury into the environment, and the Sierra de Perijá park, an area for coal mining which has disfigured the ecosystem and put a strain on the survival of the tribes of Indians settled there. Coastal and lake areas also show signs of degradation: the mining and oil industry and the incorrect treatment of discharges have deteriorated the waters of the lakes of Maracaibo and Valencia and of the Caribbean Sea. However, sensitivity to the problem of safeguarding the Venezuelan natural heritage has ancient roots: the early twentieth century. Law for woods and mountains, the Henri Pittier National Park was established in 1937, and the 1961 Constitution already had the conservation of local resources among its priorities. The specific laws that set up the Ministry of the environment and the park system are instead of the seventies and eighties. Protected areas cover 49.5% of the territory and include over 40 national parks and over 30 natural monuments, which are the two main categories according to local legislation; numerous other reserves are also included in the system. The ecosystems protected in these localities contain a great variety of animal species that reflect the heterogeneity of the vegetal mantle; there are mammals such as giant otter, puma, jaguar, giant armadillo, ocelot, chironetto, giant anteater, satanasso chiropote, kinkajù, taira, opossum, spectacled bear; migratory sea birds and birds of mountain areas, such as cormorant, pivere, sula, tern, flamingo, osprey, pelican, magpie, hummingbird, condor of the Andes; reptiles, such as various turtles, caiman, cascavel, boa, anaconda and other snakes; amphibians such as frog, toad and dendrobat; corals, tropical fish, molluscs and crustaceans. Canaima National Park was declared a UNESCO World Heritage Site in 1994. It is an area of 3 million hectares, located in the state of Bolívar, at an altitude between 400 and over 2800 m sm The park includes a vast territory within the Guayana massif populated by endemic and endangered species. Other Venezuelan sites of international interest are the Upper Orinoco-Casiquiare Biosphere Reserve and five wetlands of the Ramsar program: Los Roques islands, Ciénaga de Los Olivitos, Cuare, Laguna de la Restringa, Laguna de Tacarigua. The country also boasts the presence in the territory of the Foundation for the defense of nature (FUDENA), an NGO established in 1975 by Venezuelans in order to promote the protection of the national natural heritage.