The Sierpe and Parismina rivers flow into the sea south of Tortuguero. The former is short, but the Parismina with its several branches is a child of Irazú. Its lower course is sometimes considered to be a part of the River Reventazon, which however has its confluence with the former a few miles from the sea.
The Reventazon River has carved its way to a profound depth around the south and southeastern bases of Irazú and Turialba, and, flanking the latter volcano, it turns northward to join the Parismina. It receives many tributaries from the northern slope of the Talamanca range, and interweaves its head waters with those of the Rio Grande de Tarcolles and the Rio Grande de Pirris, which flow into the Pacific Ocean.
The Pacuare River, once known as Suerre, enters the sea about half way between the mouth of the Reventazon and that of the Matina. Its waters, in 1630, instead of flowing to the sea, joined the Reventazon, closing the port of Suerre, but in 1651 Governor Salinas closed the northern channel, deflecting its waters and restoring the port.
The Matina River is a short stream with a large volume of water, which enters the sea just north of Port Limon near the roadstead of Moin, where, up to 1880, ocean craft anchored. The River Matina is navigable by small steamers over the bar and by large ones above the bar to the point where it receives its principal affluents, the Chirripo, Barbilla and Zent. It yearly overflows its lower valley, depositing an inch or two of exceedingly fertile mud highly appreciated by the banana planters.
The entire mainland of the coast, from the River Colorado to the Matina, is separated from the Caribbean Sea by a continuous narrow sand bank, between which and the mainland is a lagoon, said to be navigable the whole distance by boats. The intermediate rivers pour into this narrow lagoon, driving their currents across it, and, cutting through the sand bank, enter the sea. Sometimes a violent gale closes one of the openings, which are all shallow, but the river again forces an exit to the ocean through the obstruction. This whole coast for sixty-five miles, is forbidding and dangerous, and has but little depth of water within a mile of the shore, upon which a monotonous, heavy surf breaks during the entire year. It is only frequented from April until August by fishermen, who find their way to the River San Juan through the intricate system of rivers and caños described.
Port Limon, in latitude 10° north and longitude 83° 3′ 13″ west from Greenwich, is the only port of entry of Costa Rica on the Caribbean Sea. The first house was built there in 1871. The harbor faces the south, and is formed by a little peninsula on which Limon is situated. It is behind a narrow coral reef. The site, which now has perhaps 3500 to 4000 population, is being raised with earth about four feet, and its port will become one of the smoothest of the Caribbean Sea. A small island, called Uvita, lies east at a distance of 3660 feet from the town. Port Limon has a wooden pier 930 feet long, accommodating two sea-going ships, but an iron pier is about to replace it, which will berth four large ones of deep draught.
The Talamanca coast lying south of Limon is low, flat and swampy, except where it is broken by hills. The little River Banana is the first one met with going south, and its valleys produce large quantities of timber and bananas. Next comes the Estrella, also a short stream; then follows the Teliri, called in its lower course the Sicsola. It is the largest stream in Costa Rica south of Port Limon. It runs along the southern base of the great eastern mountains of the Talamanca range, through a spacious, undulating, wooded valley of 100 to 150 square miles area, partly low grounds in some places dry and in others swampy. It has several branches, like the Uren coming from the slopes of the Pico Blanco, the Supurio and others. At the entry of the high valleys of the Teliri and Coen rivers, the pyramid-like mountains of Nefomin and Nenfiobete appear, at the foot of which the interior plain of Talamanca, fifteen kilometers in length and eight kilometers in width, extends from southwest to northeast, and so uniformly that the water courses run indifferently and frequently change their beds.
Southward of Sicsola is the Tilorio or Changuinola, which makes a turbulent way to the sea from the Talamanca mountains. Along its lower margin mud flats spread to a great width, and, from its mouth towards the northwest, cover a region which surrounds also the lagoon of Sansan, and extends up the rivers Zhorquin and Sicsola. Behind the muddy zone the lands rise rapidly into hills, which in a few miles reach an altitude of several thousand feet, at times intermingling with the Cordillera. Along the entire sea margin of Talamanca runs a narrow sand-belt of firm land, at times not a hundred feet wide, like that described between the Matina and San Juan rivers.
Within this sand-belt are long, narrow, deep lagoons filled with half-stagnant water from the mud flats. These lagoons usually open into the rivers which descend from the mountains.
Between the Sicsola and the Tilorio lies the already mentioned, crooked and deep lagoon called the Laguna de Sansan.