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Cost-effective floating wind turbines with efficient installations are highly desired in deep waters (>50m). This paper presents a submerged floating offshore wind turbines (SFOWT) concept for intermediate water depths (50–200m). The performance of SFOWTs can be improved through a judicious choice of configuration, pretension, and mooring line layout. Four SFOWTs with different configurations and a similar mass, named Cyl-4, Cub-4, Cyl-3, and Hex-3, were designed and analyzed. The responses of the four SFOWTs were predicted under operational condition and extreme condition. The results show that the four SFOWTs exhib-ited good performance under both conditions. The effect of platform configurations on power output was negligible under the opera-tional condition. Under the extreme condition, among the four SFOWTs, the mean bending moments at the tower base were very close, while the maximum values differed by up to 21.5%, due to the configurations. The effect of wind-wave misalignment under the extreme condition was further analyzed. In general, the motion performances of the four-pontoon SFOWTs, Cyl-4 and Cub-4, were superior to those of the three-pontoon SFOWTs, Cyl-3 and Hex-3. Optimization studies of the mooring system were carried out on Cub-4 with different mooring line pretensions and four mooring layouts. The optimized Cub-4 could reduce the maximum motion responses in the surge, heave, and yaw by 97.7%, 91.5%, and 98.7%, respectively.