Coca forms the provisional boundary line between Ecuador and Colombia from its source to the Napo. The Aguarico also rises on the eastern slopes of the Andes north of Cayambe and flows south-eastward to a junction with the Napo in about long. 75° W., its length being roughly estimated at 420 m. Little is known of its course, or of the country through which it flows, which is provisionally occupied by Colombia. The Curaray has its sources in the defiles of the Cerros de Llanganati, and flows south-eastward to the Napo, its length being estimated at 490 m. Its lower course is sluggish, where its waters are made unpalatable by a reddish slime. The Napo and its tributaries are celebrated in the early history of South America as the route by which Gonzalo Pizarro and Orellana first reached the Amazon, and it was afterwards the principal route by which the early expeditions across the continent at this point connected the Andean Plateau with the Amazon. The other rivers which flow through the Oriente territory of Ecuador into the Marañon are the Tigre, Pastaza, Morona and Santiago. The Tigre, of which little was known until a recent date, is formed by the confluence of the Cunambo and Huiviyacu, whose sources are on the eastern slopes of the Andes near those of the Curaray. Its length below this confluence is 416 m., into which are received 109 tributaries, the largest of which are the Pucacuro and Corrientes. The Tigre is navigable at all stages up to the Cunambo confluence, and promises to afford one of the most valuable river routes in Ecuador. It enters the Marañon very near the 74th meridian. The Pastaza, or Pastassa, unlike the rivers already described, has its source on the central plateau west of the principal chain of the Andes, within the shadow of Cotopaxi, and breaks through the Cordillera to the north of Tunguragua. After flowing southward along the base of the high Andes for a short distance and receiving a number of torrents from the snowclad heights, it turns south-eastward across the plain and enters the Marañon about 70 m. above the mouth of the Huallaga. The stream is known as the Patate down to its junction with the Chambo, near Baños, and is not called Pastaza until the Agoyan falls are passed. It was navigated by Don Pedro Maldonado as early as 1741, and is navigable for steamboats of 2 to 4 ft. draft up to the mouth of the Huasaga (about 124 m.) in times of high water, and for canoes nearly 200 m. farther. The Pastaza, however, is subject to irresistible floods caused by the sudden rising of the mountain torrents on its upper course, especially the Toro, which sweep down with such fury that navigation on the river is practically impossible. The shallowness of the lower stream, where the current is sluggish, is probably due to the great quantities of silt brought down by these floods. Many of the rivers of eastern Ecuador are subject to similar floods from the Andean slopes, which have cut away broad, deep channels, through the adjacent plains, leaving long, narrow ridges between their courses which the natives call cuchillas. The Morona is formed by the confluence of the Manhuasisa and Cangaima about 310 m. above its mouth, and is freely navigable for small steamboats to that point. The two confluents just mentioned have their sources in the Andes, and flow for some distance across the plain before uniting to form the Morona. Both are navigable for considerable distances. The Morona follows a very tortuous course before entering the Marañon, at long. 70° W., and receives a large number of affluents, one of which serves as the outlet for Lake Rimachuma, in Peruvian territory. Very little is definitely known of the affluents of the Morona, Pastaza and Tigre, as the territory through which they run has been but slightly explored. The Santiago, which enters the Marañon near the Pongo de Manseriche, is formed by the confluence of the Paute, which rises in the province of Azuay, and the Zamora, which has its source among the mountains of Loja. According to Alexander Garland (Peru in 1906), the rivers of eastern Ecuador are navigable at low water for steamers of 2 to 4 ft. draft for an aggregate distance of 1503 m., as follows:—
| Miles. | |
| Napo, to the mouth of the Aguarico | 559 |
| Curaray, up to Canonaco | 286 |
| Tigre, up to Cunambo-Huiviyacu confluence | 416 |
| Pastaza | 31 |
| Morona, up to the Rarayacu | 211 |
These same rivers are navigable at high water for steamers of 1912 ft. draft for an aggregate distance of 1330 m., including 68 m. of the Aguarico, and for steamers of 2 to 4 ft. draft for an additional 733 m. The last aggregate includes an extension of 93 m. on the Pastaza, 99 on the Morona, 186 on the Napo, and the balance on the Manhuasisa, Cangaima, Pucacuro, Corrientes, Cunambo and Huiviyacu.
On the western versant of the Andes of Ecuador there are three river systems of considerable size—the Mira, the Esmeraldas and the Guayas. The sources of the first—the Rioblanco, Pisco and Puntal—are to be found on the northern slopes of the transverse ridge which culminates in the Imbabura volcano. Its course is north and north-west to the Colombian frontier, thence westward and north-west to the Pacific, breaking through the Western Cordillera on its way. It forms the boundary line for some distance between Ecuador and Colombia, but near its mouth where the river turns northward Colombia has taken possession of the left bank and all the territory covered by its large delta. Its principal tributaries on the left are the San Pedro, Paramba, Cachiyacu, Chachavi and Canumbi, and on the right the San Juan, Caiquer and Nulpe. The delta channels of the Mira are navigable, being tributary to the Colombian port of Tumaco. The Esmeraldas drains all that part of the central plateau lying between the transverse ridge of Tiupullo on the south, and the Imbabura ridge on the north, together with the western slopes of the Cordillera between Iliniza and Cotocachi, and a considerable part of the lower plain. It is formed by the confluence of the Quininde and Toachi with the Guaillabamba between 40 and 50 m. above its mouth, and discharges into the Pacific in lat. 1° N., long. 79° 40′ W., through a narrow and precipitous gorge. The volume and current of the river is sufficient to freshen the sea 2 m. from the coast. The Guaillabamba is the larger and more important tributary, and should be considered the main stream. It rises in the Chillo valley in the vicinity of Cayambe, and flows across the northern end of the central plateau, breaking through the Western Cordillera between Cotocachi and Pichincha. One of its plateau tributaries, Rio Pedregal, rises on the slopes of Cotopaxi and is celebrated for its three beautiful cascades, the highest of which is about 220 ft. The Toachi and Quininde have their sources on the western slopes of the Cordillera. The Guayas or Guayaquil river is in part an estuary extending northward from the Gulf of Guayaquil, bordered by mangrove swamps and mud banks formed by the silt brought down from the neighbouring mountains. All the bordering country on both sides is of the same description, and for a long distance inland extensive areas of swampy country are submerged during the rainy season. Above the mouth of the Daule the river is known as the Bodegas, which in turn is formed by the confluence of the Babahoyo and the Vinces. The Guayas also receives a large tributary from the east called the Yaguachi. All these streams are navigable on their lower courses, regular steamboat communication being maintained on the Guayas and Bodegas to a river port of the latter name, 80 m. above Guayaquil, and for 40 m. on the Daule. The navigable channels of all the rivers are computed at 200 m. The drainage basin of the Guayas, according to Theodor Wolf, covers an area of 14,000 sq. m., and includes the greater part of the lower plain and the western slopes of the Cordillera Occidental as far north as Iliniza. The Babahoyo, which is the main stream, has its sources on the slopes of Chimborazo, the Daule on the Sandomo ridge in the latitude of Pichincha, the Yaguachi on the south-eastern slopes of Chimborazo, whence it flows southward for a considerable distance before breaking through the Cordillera to the western plain. The Guayas is one of the most interesting and varied of the South American river systems, and is of great economic importance to Ecuador. In addition to these three river systems, there are a large number of short streams on the coast flowing into the Pacific and Gulf of Guayaquil, only two of which have any special importance in the present undeveloped state of the country. These are the Santiago, which drains several fertile valleys in northern Esmeraldas and western Carchi, and whose outlet is connected with some navigable tide-water channels, including the Pailon basin and the Caráquez, or Caracas, on which is located the village of Bahia de Caráquez (lat. 0° 34′ S.), the nearest port to the city of Quito.
There are a considerable number of small lakes in Ecuador, but no large ones. These are of two classes—those of the bowl-like valleys and extinct craters of the mountainous region, and the reservoir lakes of the lowland plains caused by the annual overflow of the rivers. It is impossible to say how many of the latter there may be, for much of the territory Lakes.where they are found is unexplored. They are usually shallow and malarial. Among the upland lakes, there are some of special interest because of their position and historical association. The Yaguar-cocha (“lake of blood”), in the province of Imbabura, near Ibarra, which is only 112 m. in circumference, is celebrated for the tradition that Huayna-Capac, one of the great conquerors of the Inca dynasty, defeated an army of rebellious Carranquis on its shores, and threw so many of their bleeding corpses into it as to turn its waters to the colour of blood. On the south-east skirt of Cotocachi, 10,200 ft. above the sea, is the beautiful little Cuy-cocha, which originated, it is believed, through the falling in of the mountain’s sides. There are two others of apparently the same origin on the north-west slopes of the Mojanda volcano, but they are less attractive because of their gloomy surroundings. In the deep valley between the mountains of Imbabura and Mojanda is the lake of San Pablo, 8848 ft. above the sea. It is one of the largest of its class, being about 5 m. in circumference, and is situated in an exceptionally fertile region. It drains through the Peguchi into the Rio Blanco, a tributary of the Mira. Other well-known lakes of the plateau region are Quirotoa, about 4600 ft. in diameter; Colta, east of Riobamba, and Colay, south of the same place. Among the many thermal springs throughout the Andean districts, the best known are at Belermos and San Pedro del Tingo, north-east of Quito; at Cachillacta, in the district of Nanegal; at Timbugpoyo, near Latacunga; at Baños (5906 ft. elevation), near the foot of Tunguragua; and on the slopes of Rumiñagui and Chimborazo.
The coast of Ecuador extends from about lat. 1° 20′ N. to the vicinity of the Boca Jambeli on the southern shore of the Gulf of Guayaquil, in lat. 3° 14′ S., and has an outward curve. Its more prominent headlands are Punta Galera, Cabo Pasado, Cabo de San Lorenzo and La Puntilla, or Santa ÉlenaCoast.