The Merchant Mariner Credential (MMC) is a credential issued by the United States Coast Guard in accordance with guidelines of the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) to United States seafarers in order to show evidence of a mariner's qualifications. It is the standard documentation required for all crew members of U.S. ships for all vessels required to operate with a licensed Master or Operator, regardless of size. The MMC replaced the Merchant Mariner's Document, merchant mariner license, Certificate of Registry, and STCW Certificate.

The Transportation Worker Identification Credential program is a Transportation Security Administration (TSA) and U.S. Coast Guard initiative in the United States. The TWIC program provides a tamper-resistant biometric credential to maritime workers requiring unescorted access to secure areas of port facilities, outer continental shelf facilities, certain manufacturing facilities, and vessels regulated under the Maritime Transportation Security Act of 2002, or MTSA, and all U.S. Coast Guard credentialed merchant mariners. As of May 2014, there were 2,999,058 people enrolled in the program. Those seeking unescorted access to secure areas aboard affected vessels, and all Coast Guard credentialed merchant mariners, must obtain a TWIC. The new measures were fully implemented on April 15, 2009. To obtain a TWIC, an individual must provide biographic and biometric information such as fingerprints, sit for a digital photograph and successfully pass a security threat assessment conducted by TSA.