Dependence of Thermal Comfort of Diving Suit on Neoprene Properties and Diving Depth.

Neoprene wetsuits experience significant thermal resistance degradation under hydro-static pressure, compromising diver safety and thermal comfort. Despite this known limitation, quantitative predictive models correlating material properties with thermal performance under diving conditions remain underdeveloped. This study quantified thermal resistance changes in commercial neoprene under simulated diving pressure (50, 100, 150, and 200 kPa, equivalent up to a 20 m depth) and developed predictive models for thermal performance degradation. A total of 33 commercially available neoprene sheets representing 11 types in nominal thicknesses of 3, 5, and 7 mm were systematically analyzed. Mass per unit area, thickness, and thermal resistance (Rct) were measured under ambient conditions, as was compressive displacement under 50, 100, 150, and 200 kPa compressive loads. Multiple regression analysis established relationships between material properties and thermal performance. Under 200 kPa compression, neoprene samples exhibited compressive displacement ranging from 52.8% to 72.9% (mean: 64.3%). Strong correlations were observed between thermal resistance and thickness (r = 0.9198) and mass per unit area (r = 0.89388). The developed multiple regression model accurately predicted thermal resistance under compression. The 200 kPa pressure-induced thermal resistance reduction ranged from 19.3% to 53.2%, with an average decrease of 40.9%. Even at a pressure of 50 kPa, which corresponds to a diving depth of only 5 m, the thermal resistance of neoprene will be reduced by 21.5% on average. Commercial neoprene demonstrates substantial and predictable thermal performance degradation under diving pressure. The established correlations and predictive models enable evidence-based wetsuit selection and diving safety assessment. These findings highlight the critical need for pressure-resistant thermal insulation technologies and updated diving safety protocols accounting for depth-dependent thermal protection degradation.