What happens if unforeseen major events occur before the vessel leaves port?

The correct answer highlights a fundamental principle in maritime contracts known as the doctrine of supervening impossibility or frustration of purpose. If unforeseen major events occur before the vessel leaves port, such as natural disasters or significant political unrest that fundamentally alter the circumstances of the charter agreement, the charterer may have the right to cancel the contract. This cancellation effectively extinguishes all actions related to the agreement, as it acknowledges that the terms can no longer be fulfilled in the manner anticipated.

This principle exists to protect both parties in the contract, recognizing that certain events are beyond their control and could invalidate the feasibility of the agreed-upon voyage. Such unforeseen circumstances allow for a legal release from obligations, ensuring that neither party is unfairly held to terms that have become impractical or impossible due to significant changes in conditions.

In contrast, the other options do not accurately reflect the legal ramifications of unforeseen events in maritime contracts. The application of extra charges, continuing the voyage as planned, or placing the decision solely in the captain's hands do not align with the established provisions for handling unpredictable and significant disruptions that affect the charter agreement prior to departure.