We find Hiawatha standing at the door of his wigwam looking out at the world and thinking. All of the sadness is gone from his face. He even has a look of triumph.
It turns out that the giant floating canoe (i.e., the ship) of the white people is coming toward him on the water.
A man called the "Black-Robe chief" gets off the boat, and we can probably tell from his black robes that he is some sort of priest.
Hiawatha greets the men kindly and offers them everything they need. The men have trouble understanding him, although one or two can half-guess what he's saying.
The white men bring news of Jesus Christ, which Hiawatha almost immediately accepts as the true faith. (You can thank Longfellow for indulging his Christian bias a bit with that one. )
Hiawatha brings out his peace-pipe and sits smoking with the white visitors.
While the white men have a nap, Hiawatha sneaks away and tells his grandmother that he's going on a long journey. He asks Nokomis to make sure that no harm ever comes to the white people. He also makes sure to call together all his friends and warriors to tell them about his long trip. He plans on heading west.
With all that said, Hiawatha gets into his birch canoe and paddles away from his people, not knowing when, or if, he'll ever return.
The people of Hiawatha's village watch him until he's gone.