In Port Kakule the greatest rise of tide is seven feet.  In Surigao Strait the flood tide sets to the west, and the ebb to the east.  The velocity of the stream in the strait reaches six knots at springs.  There is a difference of about two hours between the time of high water at Surigao and in Surigao Strait.  Fishermen roughly estimate that when the moon rises the ebb tide commences to run in Surigao Strait.  From January to June there is but one high water during the twenty-four hours, in Surigao Strait, which occurs during the night.  From July to December the same phenomenon takes place, but the time of high water is by day.

From observations made by the Spanish surveyors, it appears that the highest tide on the west coasts of the islands of the strait takes place at the same hour as the lowest tide on the east coasts.

The Mindanao river disembogues five miles to the south of Palak Harbor by two wide arms, on the northernmost of which is the town of Kota-batu, about 5 1/2 miles from the mouth.  The river is navigable for 60 miles by vessels of 3 1/2 feet draught; it flows through a beautiful valley 30 miles in width, which scarcely shows any change of level; the valley is capable of producing tobacco, cacao, sugar, maize, and cotton; but this is only known at present by specimens produced.  The course of the river lies SE. for 45 miles from its mouth to the lake Ligauasan, out of which it is seen to flow; from the other side of the lake the direction of the river is NNE. to its source in the Sugut Mountains.  At 21 miles from the northern mouth the river divides into two arms, which enter the sea 4 1/2 miles apart.

In the northern part of Mindanao is the province of Surigao, bordered on the north by the Surigao Sea, on the east by the Pacific, on the south by the District of Davao, and on the west by the territory of the infieles.  It is mountainous, but the Christian population resides on the coasts and in the northern point of the territory.  The population is 95,775, distributed among 45 pueblos, 10 barrios, and 30 rancherias of subdued infieles.  Abaca and palay are raised, and in the gold washings considerable gold of good quality is found.

Military notes on the Philippines affirm that the islands are, in many respects, Spain’s best possessions, due to the abundance and variety of products, numerous and good ports, character of inhabitants, and on account of the vicinity of certain countries of eastern Asia, which are now entering upon a stage of civilization and commerce.  The group is composed of some 2,000 islands.  In 1762 Manila was taken and held by the English for a ransom of 1,000,000 pounds sterling.  This, however, was never paid, and the islands were finally returned to Spain.

The archipelago extends from 5 degrees 32 minutes to 19 degrees 38 minutes, north latitude, and from 117 degrees to 126 degrees, east longitude.  It thus covers about 1,000 miles north and south and 600 east and west.