The present town of San Carlos consists only of some twenty cane or board houses, occupied chiefly by the officers of the customs, and the soldiers with their families. Since the seizure of San Juan, the customs on goods entering the State, via that port, have been collected here. This circumstance, together with the fact that all the boats passing through the river stop here to unship or resume their masts, and renew their supplies, makes it a place of some importance. It is delightfully situated, and from the corridor of the commandant’s house, one of the finest views in the world is presented to the traveller. The broad lake spreads like a mirror in front, its opposite shores marked by the regular volcanic peaks of Orosi, Madeira, and Ometepec, capped with clouds, which rise dim and blue in the distance. Nearer lie the fairy-looking islands of La Boqueta, golden under the tropical sun, while in the foreground the emerald shores stretch their wide arms on either side, a fit setting for so gorgeous a picture. Immediately opposite the town, flowing into the lake, within a few rods of where the San Juan flows out, is the Rio Frio, Cold River, whence the water for consumption in the village is brought. The sources of this river have never been explored, but they are supposed to be somewhere in the mountains of Costa Rica. A tribe of Indians, called the _Guatusos_, who hold no communication with the whites, inhabit its banks, and resist all attempts at exploration. The late commandante of the fort, Don Trinidad Salazar, endeavored to ascend the stream a few months previously to our arrival; but on the sixth day he was interrupted by a large body of Indians, and after a sharp contest, in which he was severely wounded, was compelled to retreat. He subsequently gave me a glowing account of the beauty of the stream, and the fertility and luxuriance of its shores. It has a depth of two fathoms of water, for a distance of forty miles above its mouth, and from his account, it could probably be navigated by steamers for twice that distance. The fact that a stream of this size, and the wide extent of country around it, are wholly unknown, would seem to show how much remains to be discovered in Central America, and how broad a field it holds out for enterprise and adventure. Between the mouth of the Rio Frio and the source of the San Juan, is a broad sand-bar, which seems to be a grand sunning-ground for alligators. Hundreds congregate here during the dry season, when the bar is exposed, and they appear to have an exceedingly good time of it. We could distinctly see their ugly, black carcasses from the commandante’s corridor; and our host showed us a basket of their teeth, which he had picked up on the bar, and which were more pleasant to contemplate in that condition, than when adorning the jaws of the living reptile.