The river was flowing in a westerly and south-westerly direction, the banks showing a quantity of rubber trees all along. A tiny islet 50 m. long had been eroded from the right bank, just above a strong corrideira, easily identifiable by later travellers who may visit it, since a huge rock stands there in the centre of the river.
On the left side of the river foliated rock 10 ft. high was exposed for the length of 1 kil. Dense forest was to be seen on both sides of the river all along the rapids.
Two more islands, each 100 m. in diameter—Romeo and Juliet Islands—close to each other, were then seen on one side of the main channel, which was 200 m. wide.
From this point the river actually flowed in a S.S.W. direction (230° b.m.), and for 2,500 m. we had to negotiate strong and troublesome rapids with variations of shallow water, usually with a bottom of sharp rocks. The water in many of those places, coming with great force, hit the bottom and was thrown up again in high waves which swamped our canoe each time we went through them. In one place we got stuck on a rock in the middle of the foaming waters, and had a hard job to get the canoe off again and prevent her sinking when we had done so.
Where the river turned for another 2 kil. 500 m. more to the west, another elongated island rose on the left side of the stream. The island—Laurita Island—was only 80 m. broad, but had a total length of 1,800 m.
More rapids and shallow water above a bottom of red volcanic débris were found. A small tributary 2 m. wide at the mouth entered the Arinos on the left bank, not far from the spot where a rocky rugged island rose in the centre of the stream.
I halted at 11.30 in order to take the usual observations for latitude and longitude and soundings of the river. The stream, which was 320 m. broad, below some rapids, showed a depth of 6 ft. the entire way across. Farther down, where it contracted to 200 m. in breadth, it showed a depth of 8 ft. in the centre with a maximum depth of 10 ft. to the right and left of it, gradually decreasing to 5 ft., 3 ft., 2 ft., and 1 ft. as it neared the banks. Lat. 11° 7′·3 S.; long. 57° 46′ W.
A Giant Central Wave emerging from a Narrow Channel.