From Cape Mala Pascua to Point Aguila, which forms the southwest angle of the island, 16 rivers discharge their waters on the south coast.

On the west coast 3 rivers, 5 rivulets, and several fresh-water lakes communicate with the sea.  In the small extent of 330 leagues of area there are 46 rivers, besides a countless number of rivulets and branches of navigable water.

The rivers of the north coast are stocked with delicious fish, some of them large enough to weigh two quintals.

From the river of Arecibo to that of Manati, a distance of 5 leagues, a fresh-water lagoon, perfectly navigable for small vessels through the whole of its extent, runs parallel to the sea at about a mile from the shore.

In the fertile valley of Anasco, on the western coast, there is a canal formed by nature, deep and navigable.  None of the rivers are of real military importance; for, though considering the shortness of their course, they attain quite a volume, still it is not sufficient for good-sized vessels.

The rivers emptying on the north coast are Loisa, Aguas Prietas, Arecibo, Bayamon, Camuy, Cedros, Grande, Guajaraca de la Tuna, Lesayas, Loquillo, Manati, Rio Piedras, Sabana, San Martin, Sibuco, Toa, and Vega.

Those emptying on the east coast are Candelero, Dagua, Fajardo, Guayanes, Majogua, and Maonabo.

On the south coast:  Aquamanil, Caballon, Cana, Coamo, Descalabrado, Guanica, Guayama, Guayanilla, Jacagua, Manglar, Penuela, Ponce and Vigia.

On the west coast:  Aguada, Boqueron, Cajas, Culebrina, Chico, Guanajibo, Mayaguez, and Rincon.

The limits of the Loisa river are:  On the east, the sierra of Luquillo (situated near the northeast corner of the island); on the south, the sierra of Cayey, and on the west, ramifications of the latter.  It rises in the northern slopes of the sierra of Cayey, and, running in a northwest direction for the first half of its course and turning to northeast in the second half, it arrives at Loisa, a port on the northern coast, where it discharges its waters into the Atlantic.  During the first part of its course it is known by the name of Cayagua.

The Sabana river has, to the east and south, the western and southern limits of the preceding river, and on the west the Sierra Grande, or De Barros, which is situated in the center of the general divide, or watershed.  It rises in the sierra of Cayey, and, with the name of Pinones river, it flows northwest, passing through Aibonito, Toa Alta, Toa Baja, and Dorado, where it discharges into the Atlantic to the west of the preceding river.

The Manati river is bounded on the cast and south by the Sierra Grande and on the west by the Siales ridge.  It rises in the Sierra Grande, and parallel with the preceding river, it flows through Siales and Manati, to the north of which latter town it empties into the Atlantic.

The Arecibo river is bounded on the east by the Siales mountain ridge, on the south by the western extremity of the Sierra Grande, and on the west by the Lares ridge.  It rises in the general divide, near Adjuntas, and flows north through the town of Arecibo to the Atlantic, shortly before emptying into which it receives the Tanama river from the left, which proceeds from the Lares Mountains.