Terminal Teluk Lamong (TTL) in Indonesia is a company that operates in service sector managing a multipurpose terminal. It provides various services such as loading and unloading containers and dry bulk using integrated crane tools that employ the first semi-automatic facilities and infrastructure in Indonesia. Crane operators’ work involves risks of work accidents because they operate at heights and their job tasks require high concentration. This study aimed to find out fatigue levels and mental workloads typical for workplaces of crane operators and to analyze and assess working conditions. The study results gave grounds for developing recommendations on how to improve workplaces of STS and GSU crane operators who deal with loading and unloading containers and dry bulk cargoes at a seaport. The relevant data were obtained by questioning 56 STS and GSU crane operators working in four shifts, 6 hours each. We used an employee identity questionnaire as well as SOFI and NASA TLX questionnaires. The results were analyzed to obtain scores for estimating fatigue levels and mental workloads. Statistical analysis involved correlation and regression tests on two variables on STS and GSU crane operators. Upon completion, some recommendations were suggested as regards necessary changes into work process and longer rest in order to reduce fatigue and mental workloads for operators. The SOFI questionnaire established medium fatigue levels of STS and GSU operators but mental workloads turned out to be high. The correlation test did not reveal any correlation between fatigue and mental workloads for STS crane operators. It was shown that fatigue could be overcome by adequate rest, well-balanced diet rich with nutrients, and relevant exercise. At the same time, arranging work shifts more rationally, socializing, and training on the importance of fatigue awareness can reduce high mental workloads. The study results can help prevent or reduce increased fatigue and mental workloads that can lead to work accidents.