I had determined to anchor at Caldera, a small port on the south-west side of Mindanao, about ten miles distant from Zamboanga, where the governor resides.  The latter is a considerable place, but the anchorage in its roadstead is said to be bad, and the currents that run through the Straits of Basilan are represented to be strong.  Caldera, on the other hand, has a good, though small anchorage, which is free from the currents of the straits.  It is therefore an excellent stopping-place, in case of the tide proving unfavorable.  On one of its points stands a small fort, which, on our arrival, hoisted Spanish colors.

At six o’clock we came to anchor at Caldera, in seven fathoms water.  There were few indications of inhabitants, except at and near the fort.  An officer was despatched to the fort, to report the ship.  It was found to be occupied by a few soldiers under the command of a lieutenant.

[Caldera fort.] The fort is about seventy feet square, and is built of large blocks of red coral, which evidently have not been taken from the vicinity of the place, as was stated by the officers of the fort; for although our parties wandered along the alluvial beach for two or three miles in each direction, no signs of coral were observed.  Many fragments of red, gray, and purple basalt and porphyry were met with along the beach; talcose rock and slate, syenite, hornblend, quartz, both compact and slaty, with chalcedony, were found in pieces and large pebbles.  Those who were engaged in dredging reported the bottom as being of coral, in from four to six or eight fathoms; but this was of a different kind from that of which the fort was constructed.

The fort was built in the year 1784, principally for protection against the Sulu pirates, who were in the habit of visiting the settlements, and carrying off the inhabitants as slaves, to obtain ransom for them.  This, and others of the same description, were therefore constructed as places of refuge for the inhabitants, as well as to afford protection to vessels.

Depredations are still committed, which render it necessary to keep up a small force.  One or two huts which were seen in the neighborhood of the bay, are built on posts twenty feet from the ground, and into them they ascend by ladders, which are hauled up after the occupants have entered.

These, it is said, are the sleeping-huts, and are so built for the purpose of preventing surprise at night.  Before our arrival we had heard that the villages were all so constructed, but a visit to one soon showed that this was untrue.  The natives seen at the village were thought to be of a decidedly lighter color and a somewhat different expression from the Malays.  They were found to be very civil, and more polished in manners than our gentlemen expected.  On asking for a drink of water, it was brought in a glass tumbler on a china plate.  An old woman, to whom they had presented some trifles, took the trouble to meet them in another path on their return, and insisted on their accepting a basket of potatoes.  Some of the houses contained several families, and many of them had no other means of entrance than a notched post stuck up to the door.