Spinal cord injuries (SCI) often result in impaired motor functions. To quantify these impairments, swimming patterns were analyzed in individuals with SCI. Water provides a unique rehabilitation environment where buoyancy supports weight-bearing activities and can reveal deficits that might otherwise go unnoticed. Data were collected of 30 individuals with chronic, motor-incomplete SCI and 20 healthy controls during breaststroke swimming on a kickboard. Using eight wearable inertial sensors attached to the lower limbs, we captured detailed kinematic data. Spatiotemporal parameters were then calculated and compared between the two groups to assess differences in swimming patterns. An analysis of the parameters revealed significant differences in velocity (p < 0.001, ε² = 0.476) and distance per stroke (p < 0.001, ε² = 0.516), indicating decreased swimming speeds in individuals with SCI compared to controls. Furthermore, individuals with SCI demonstrated a reduced range of motion (RoM) in the ankle (p = 0.003, ε² = 0.516) and knee joints (p = 0.041, ε² = 0.142). The limited RoM likely contributes to the shorter distance covered per stroke. These observations underscore the impact of SCI on functional capabilities. The developed algorithm holds promise for enhancing the assessment of motor deficits after neurological injuries.