Which document must be maintained as part of a mariner’s records?

The Merchant Mariner Credential (MMC) is a vital document that serves as the official identification and certification for mariners in the United States. It outlines the qualifications, endorsements, and service history of the mariner, which are essential for operating vessels and performing various duties at sea. Maintaining the MMC as part of a mariner's records is crucial because it is a legal requirement for working on commercially operated vessels. The MMC reflects the mariner's current qualifications and ensures compliance with U.S. Coast Guard regulations.

While other documents such as the U.S. Coast Guard License, Vessel Inspection Certificate, and Personal Seafarer Logbook are important for maritime operations and personal record-keeping, the MMC specifically serves as the primary credential recognized by the Coast Guard for mariner identification and certification. Therefore, it is essential to keep the MMC up-to-date and readily available, as it is fundamental to a mariner's professional standing and ability to work at sea.