The study compared two simulation environments for training of Swedish naval Command and Control teams by using indirect measures, including workload, combat readiness, and situation awareness. The literature explains simulation-based training as providing a safe avenue to practice relevant scenarios. Fidelity, the degree of realism in the simulation, and workload, the equilibrium between demands and assigned tasks, are crucial factors examined in this study of low- and high-fidelity naval simulations. This study was conducted to better understand the effects of various training methods. An experimental design with repeated measures was used with three consecutive escalating parts. The subjective, multidimensional assessment tool, NASA-Task Load Index was used to rate perceived workload. Combat readiness of the ship and mental demand yielded significant results. For combat readiness of the ship, there was a difference between the low and the high-fidelity setting, for the initial part of the scenario p = 0.037 and for the second part p = 0.028. Mental demand was experienced as higher in the low-fidelity setting, p = 0.036. Notably, the simulated internal battle training for onboard command teams in a low-fidelity setting was found to induce a level of stress comparable with that experienced in a high-fidelity setting. The results indicate that low-fidelity training results in a workload not distinguishable from high-fidelity training and has practical implications for increased use of low-fidelity training as part of (naval) command team training programmes.