Marguerite endures the voyage with the Basque fishermen, suffering sun-blistered skin while striving to live modestly aboard. The men, treating her as a holy woman who brings them luck, share their food and shelter; she helps clean fish, mend nets, and prays to the Virgin. For a month, calm weather carries the two boats across the sea under Aznar's stellar navigation.

In the fifth week, a violent storm strikes. Marguerite clings to a rope tied to the mast as towering waves toss the boats. She watches in horror as the sister vessel capsizes, drowning all six men aboard, including the strong swimmer Ion. Their own boat miraculously survives. When the storm passes, Aznar credits Marguerite's prayers with their salvation, though she privately denies any such power. The Virgin's picture, rosary, New Testament, and Psalms have been swept away, but she still has Claire's ring, coins, pearls, and the bear claw.

Disoriented and off course, the surviving crew quarrels bitterly until Aznar separates them with his knife. To restore peace, Marguerite plays the role of anchoress and leads them in the prayer for the dead, which calms the men. They resume sailing at dawn, accompanied by playful porpoises that the men take as a favorable sign; Aznar forbids killing one.

After two solemn weeks, they sight birds and eventually encounter a larger Basque whaling ship captained by Barthold, who speaks perfect French. He questions Marguerite about her island and supposed vow of silence; she answers honestly that she was abandoned and rescued. Barthold tells the crew they may follow him to La Rochelle, just three days away, and the fishermen cheer at the news of imminent landfall.