Augmented reality is an increasingly widespread technology. However, the potentials in areas with extraordinarily high cognitive requirements in safety-critical environments have received little attention so far. Services that necessitate extensive expertise, are safety-critical, and require the completion of concurrent tasks can be supported using augmented reality. In such cases, augmented reality enables the augmentation of service provision by giving seamless integration of information directly into the field of view while permitting for hands-free interaction in the case of head-mounted displays. This research investigates the user-centered requirements for augmented reality solutions in a safety-critical area in the operations of a large European seaport. It specifically addresses the measurement of water depths throughout the entire port area for maintenance of port infrastructure. Based on eleven think-aloud sessions during the process of water depth management, two expert interviews and two expert workshops, five requirements for augmented reality were derived that solution should fulfil to support the service. As a result, we present the first study on the applicability and practicability of augmented reality in the marine industry and provide the foundation for future research on the use of augmented reality in safety-critical contexts.