It was 20th September before preparations were completed for the eventful voyage from Bussa to the mouth of the Niger. For provisions they took three large bags of corn and one of beans, a couple of fowls, and two sheep to last a month, while the king added rice, honey, onions, and one hundred pounds of vegetable butter. Then in two native canoes the Landers embarked on the great river, the "Dark Water" as it was more often called, while the crowds who came down to the riverside to bid them farewell knelt with uplifted hands, imploring for the explorers the protection of Allah and their prophet. It was indeed a perilous undertaking; sunken reefs were an ever-present danger, while the swift current ran them dangerously near many jagged rocks. For nearly a month they paddled onward with their native guides in anxiety and suspense, never knowing what an hour might bring forth. On 7th October a curious scene took place when the King of the Dark Water came forth in all his pomp and glory to see the white strangers who were paddling down the great river. Waiting under the shade of a tree, for the morning was very hot, the Landers observed a large canoe paddled by twenty young black men singing as they rowed. In the centre of the boat a mat awning was erected: in the bows sat four little boys "clad with neatness and propriety," while in the stern sat musicians with drums and trumpets. Presently the king stepped forth. He was coal black, dressed in an Arab cloak, Haussa trousers, and a cap of red cloth, while two pretty little boys about ten years of age, acting as pages, followed him, each bearing a cow's tail in his hand to brush away flies and other insects. Six wives, jet black girls in neat country caps edged with red silk, accompanied him. To make some impression on this pompous king, Lander hoisted the "Union flag." "When unfurled and waving in the wind, it looked extremely pretty, and it made our hearts glow with pride and enthusiasm as we looked at the solitary little banner. I put on an old naval uniform coat, and my brother dressed himself in as grotesque and gaudy a manner as our resources would afford; our eight attendants also put on new white Mohammedan robes." Other canoes joined the royal procession and the little flotilla moved down the river. "Never did the British flag lead so extraordinary a squadron," remarks Lander. As the King of the Dark Water stepped on shore the Englishmen fired a salute, which frightened him not a little till the honour was explained. Having now exchanged their two canoes for one of a larger size, they continued their journey down the river.

On 25th October they found the waters of the Niger were joined by another large river known to-day as the Benue, the Mother of Waters, flowing in from the east. After this the banks of the river seemed to grow hilly, and villages were few and far between. "Our canoe passed smoothly along the Niger, and everything was silent and solitary; no sound could be distinguished save our own voices and the plashing of the paddles with their echoes; the song of birds was not heard, nor could any animal whatever be seen; the banks seemed to be entirely deserted, and the magnificent Niger to be slumbering in its own grandeur."

"One can imagine the feelings," says a modern writer, "in such circumstances of the brothers, drifting they knew not whither, in intolerable silence and loneliness on the bosom of a river which had caused the death of so many men who had endeavoured to wrest from it its secret." Two days later a large village appeared, and suddenly a cry rang through the air: "Holloa, you Englishmen! You come here!" It came from a "little squinting fellow" dressed in an English soldier's jacket, a messenger from the Chief of Bonney on the coast, buying slaves for his master. He had picked up a smattering of English from the Liverpool trading ships which came to Bonney for palm-oil from the river. There was no longer any doubt that the mouth of the Niger was not far off, and that the many-mouthed delta was well known to Europeans under the name of the "Oil Rivers" flowing into the Bight of Benin.

Lander pushed on till he had paddled down the Brass River, as one of the many branches was called, when he heard "the welcome sound of the surf on the beach."

The mystery of the Niger, after a lapse of two thousand five hundred years since its existence had been recorded by Herodotus, was solved at last.