The answer is: They made sacrifices to God

Jonah 1:16 - They probably became true converts to the God of Israel.

In an exhilarating twist of fate, after Jonah’s dramatic ordeal with the great fish, those sea-worn sailors finally got a glimpse into a divine mystery. Faced with such a furious storm, they called upon their gods to no avail, only to discover that Jonah’s God—that is the one true God—commanded even the waters. Once the tempest quieted, and the ship no longer rocked dangerously, the crew was moved to express gratitude, as is typical of those who have just faced divine intervention.

Interestingly, this act of sacrifice was a common ancient practice. In many cultures, it was believed that giving offerings after a life-threatening situation was a way to appease the deities and show profound thanks. This carries echoes of the story of the Israelites in Egypt, as they too, often offered sacrifices as a sign of fealty in times of need. The sailors likely realized that Jonah's God was not just a regional deity—his power extended beyond what they’d understood.

This sudden turn in belief reinforces a powerful theme—that truth can reach even those furthest away from it. Picture this: the crew, embodying the notion that faith knows no bounds, perhaps also contained legends of epic sea creatures similar to the giant fish. This uncanny connection between their world and Jonah’s experience highlights how diverse voices can converge in shared understanding—really, a sneak peek into God's reach throughout all the earth!