If, the sky being clear, the sun, moon, and stars come out and are higher than the horizon, it is a certain sign of land; at night heave to and sound, at daytime look out for it.
If on the route there should be thick mists ahead which do not move away, or a fixed line, or a damp fog, heave to and sound, keeping a good look-out, for there is probably land near.
If certain flashes with little lights are seen ahead, accompanied by thunder, or there are puffs of wind, it being night time, heave to and sound, as they may be signs of small rocks or islets. If the lightning is forked and the thunder loud, also heave to and sound, keeping a good look-out.
If in spite of the wind that is blowing there come dry gusts from another quarter, or with rain or hail, it is a sign of land being near; it being night time, heave to, waiting for daylight to seek for it.
If the sea appears greasy, with leaves of trees, grass, herbs, wood, branches, palm nuts, and other things which the waves carry from the shores, and rivers send down when in flood, it is a sign of land being near in the direction of the present course of the wind, or the currents have brought them. In that case the circumstances will indicate what it is best to do, but land will be left behind towards the quarter whence the wind comes.
If there are currents it is better when they are strong, or there are shoals of small fishes which seem to swarm over the sea, or patches of camarones, sea snakes, seals, turtles, much bad water, or some land birds, take care, for the ship will be very near the land.
If flocks of many sea birds are met with, such as boobies and petrels, note should be taken of the direction in which they fly, and whence they come in the morning; noticing whether they assemble early and return late, for then they are far from the land; but if they assemble late and return early, the land is near. If they are not seen to assemble, and are heard to make a noise at night, and are still to be seen at dawn, then either land is very near or the birds have slept on the sea. It is to be noted that these birds almost always frequent islets or rocks, because they are nearer their fishing grounds. For this reason there should be vigilance to avoid shoals.
If the birds that may be met with are piqueros, ducks, widgeons, gulls, estopegados, terns, sparrowhawks, flamingos or siloricos, it is a sign that the land is very near; but if there are only boobies so much care is not necessary, because these birds are found far from land, and the same may be said of boatswain birds, which fly where they please. Moreover, if all the birds, or part of them, fly together, it is a sign of proximity to land; and it should be noted whether some of these birds fly as if wounded, seeking land on one or the other side.
If patches of brown water are seen on the sea, it is a sign that there are rocks near the surface; if the patches are white, it is a sign of a sandy bottom, with little depth; a black patch is a sign of ooze and mud; and a green patch points to a bottom covered with weeds. In short, if the sea is of any other colour than the ordinary one of the ocean where there is great depth, namely, dark blue, it is necessary to exercise care, and much more if at night the sea should be heard to make sounds greater than is usual. All the above signs cause an obligation to be very careful and to get soundings; but there are two things which require more especial vigilance, and which have the most importance for the security of the voyage. It is then the principal thing to bear in mind that while all these signs point to land or to rocks; that while the birds have wings and can sleep when they like on the sea; while the fish are in their element; while the winds, the thunder and lightning, and the clouds fly through the air, it is only in God that we must put our confidence, for it is He alone who knows, and who can guide and save the people and the ship.
After anchoring in any port, a careful look-out should be kept both by day and night, for the natives are great swimmers and divers, and might wedge up the rudder, cut the hawsers, or set fire to the ship. For this reason it is well, in places where there is cause for suspicion, to have a guard in the boat at night over the buoys, or at least to visit them many times.