This river is of great importance to the inland trade of many of the eastern provinces. During the rainy season, boats of considerable size convey the produce of an extensive tract of country to the sea; and, except during the months of August, September, and October, and in seasons uncommonly dry, it bears down boats of middling or small size during the whole year, from a considerable distance above _Súra-kérta_. The boats employed in the navigation of the river are of very different sizes, and of a peculiar construction: they are very long in proportion to their breadth, have flat bottoms, and draw very little water. Those generally used in conveying the produce from one village to another in the vicinity of _Súra-kérta_, carry only a few tons, and have a temporary covering of straw mats, or _kájang_; others, more carefully constructed, have a regular roof of planks and a chamber or cabin which can be closed, and convey from fifty to one hundred tons. These are generally used by individuals in their adventures to _Grésik_ and _Surabáya_. The largest, which are the property of the prince, load nearly two hundred tons. They are employed in transporting the produce of several of the interior provinces, consisting chiefly of pepper and coffee, to _Grésik_, and return laden with salt and foreign merchandize for the consumption of the interior. They require a considerable depth of water, and can only pass when the river is swollen by continued rains. They mostly depart from _Súra-kérta_ in the month of January. Their course down the river is rapid: they generally arrive at _Grésik_ in eight days; but they can perform but one voyage in a season, as they require nearly four months to work up the stream.