It'll be dark in two minutes." The captain was right.

In tropical regions there is little or no twilight.

Night succeeds day almost instantaneously.

Before the boats were lowered and the men embarked it was becoming quite dark.

The schooner observed the movement, however, and, as she did not dare to venture through the reef in the dark, her boats were also lowered and the chase was recommenced.
The reef was passed in safety, and now a hard struggle took place, for the shore was still far distant.