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.