The Orinoco river system is one of the largest in South America, originating along the southern borders of Venezuela and Brazil, in the state of Amazonas. The exact length of the river is still undetermined, with estimates between 1,500 to 1,700 mi (2,410–2,735 km) long, making it among the world's largest river systems.

The Orinoco river basin is huge, estimated between 880,000 and 1,200,000 square km.

The name Orinoco is derived from Guarauno words meaning “a place to paddle”—i.e., a navigable place. (see map)

It flows west, next north, creating the border with Colombia, and then turns east and bisects Venezuela on its way to the Atlantic. North of the Orinoco are the vast, grassy plains called llanos. To the south of the river is almost half of Venezuela's territory. Huge tropical forest areas cover the southwestern portion part, and large portions are still virtually inaccessible. The Guiana Highlands, also known as the Guyana Shield, covers the remainder. The Guyana Shield is composed of pre-Cambriam rock, up to 2.5 billion years old, and some of the oldest on the continent. Here are the tepuis, stone plateaux rearing out of the jungle floor. The most famous tepuis are Roraima and Auyantepui, from which Angel Falls descend.

Over 200 rivers are tributaries to the mighty Orinoco which extends 1290 mi (2150 km) from source to delta. During the rainy season, the river reaches a width of 13 mi (22 km) at San Rafael de Barrancas and a depth of 330 ft (100 m).

(see map) 1000 mi (1670 km) of the Orinoco are navigable, and about 341 of those can be used for sailing large ships.

The Orinoco River is composed of four geographical zones.

Alto Orinoco

The Orinoco begins on Delgado Chalbaud mountain, a high, narrow river with waterfalls and difficult, forested terrain. (see map) The most notable fall in this area, at 56 ft (17 m) is Salto Libertador. Navigation, where possible on this part of the river, is by shallow dugout, or canoe. 60 miles (100 km) from the source, the first tributary, the Ugueto, joins the Orinoco. Farther on, the descent slows and waterfalls become rapids, fast and difficult to navigate. 144 miles (240 km) downstream, the High Orinoco ends with the Guaharibos rapids.

Amazonas is Venezuela's largest state, and contains two very large national parks, Parima Tapirapecó and Serranía de la Neblina, plus smaller parks and natural monuments, such as Cerro Autana, a tepuy south of Puerto Ayacucho, which is the sacred mountain of the Piaroa tribe who believe it to be the birthplace of the universe.

This is also the homeland of many native tribes, most famous are the Yanomani, Piaroa and Guajibo. Puerto Ayacucho, which has an airport with flights in and out of Caracas and other smaller cities, is the main gateway to the state. There are tourist and commercial facilities. Lodgings, known as camps, offer various degrees of comfort. The most well-known camp is Yutajé Camp, in the Manapiare Valley east of Puerto Ayacucho. It has its own airstrip and can accommodate up to thirty people.

Traffic in and out is by river and by air, but roads are being built up and maintained, most notably the one to Samariapo, upriver past the rapids. Take this Virtual Tour for river and landscapes from Amazonas state.