But for all Agatha's trust in Thirlwell, it was daunting to watch the laboring craft and the seas that threatened to swamp her.

They looked worse when one saw their hollow fronts and raging crests, and Agatha fixed her eyes ahead.
The haze was thinning and now and then the blurred outline of trees broke through; but one belt of forest looked like another and she speculated with some uneasiness about the chance of Thirlwell's finding the river.

If he did not find it, they would run some risk, because the men could not paddle to windward and the canoes might be smashed on a steep, rocky beach.

They ran on, and sometimes the trees got plainer and sometimes vanished, but at length, when a savage gust rolled the haze away, Agatha saw an unbroken line of rocks and foam.

It looked very forbidding and she wondered what Thirlwell would do.
"Sit as far as you can to windward," he shouted, and while she awkwardly obeyed the half-breed got up on the side of the canoe.
Agatha understood what this meant.