This chapter examines the evolving role of simulators in MET, highlighting their transition from technical training tools to comprehensive learning environments. Historically grounded in apprenticeship, MET now integrates simulation to bridge theory and practice, driven by regulatory frameworks like the STCW Convention. The chapter explores various simulator modalities and how their use reflects discipline-specific pedagogies. Through a discussion of the concept of simulator fidelity encompassing technical, psychological, and interactional aspects, the chapter examines key dimensions to consider when designing simulator training scenarios to achieve the desired goals of the exercise. With reference to an identified gap in the MET literature, specifically the lack of theoretically informed learning perspectives, the chapter utilizes the fidelity discussion to motivate another type of reflection among instructors regarding the relationship between the choice of learning goals, the choice of technology, and scenario design.