The Sixth-Generation (6G) mobile network has the potential to provide not only traditional communication services but also additional processing, caching, sensing, and control capabilities to a massive number of Internet of Things (IoT) devices. Meanwhile, a 6G mobile network may provide global coverage and diverse quality-of-service provisioning to the Maritime Transportation System (MTS) when enabled through satellite systems. Although modern MTS has gained significant benefits from Internet of Things (IoT) and 6G technologies, threats and challenges in terms of security and privacy have also been grown substantially. Tracking the location of vessels, GPS spoofing, unauthorized access to data, and message tampering are some of the potential security and privacy vulnerabilities in the 6G-IoT enabled MTS. In this article, we propose a lightweight authentication protocol for a 6G-IoT enabled maritime transportation system to efficiently assist and ensure the security and privacy of maritime transportation systems. To validate the security characteristics, formal security assessment methods are utilized, i.e., Real-Or-Random (ROR) oracle model. The findings of the security analysis show that the proposed scheme is more secure than the existing schemes.