Purpose: Maximal tests conducted on land are not suitable for the prescription of aquatic exercises, which makes it difficult to optimize the intensity of water aerobics classes. The aim of the present study was to evaluate the maximal and anaerobic threshold cardiorespiratory responses to 6 water aerobics exercises. Volunteers performed 3 of the exercises in the sagittal plane and 3 in the frontal plane. Method: Twelve active female volunteers (aged 24 ± 2 years) performed 6 maximal progressive test sessions. Throughout the exercise tests, we measured heart rate (HR) and oxygen consumption (VO[subscript 2]). We randomized all sessions with a minimum interval of 48 hr between each session. For statistical analysis, we used repeated-measures 1-way analysis of variance. Results: Regarding the maximal responses, for the peak VO2, abductor hop and jumping jacks (JJ) showed significantly lower values than frontal kick and cross-country skiing (CCS; p < 0.001; partial ?[superscript 2] = 0.509), while for the peak HR, JJ showed statistically significantly lower responses compared with stationary running and CCS (p < 0.001; partial ?[superscript 2] = 0.401). At anaerobic threshold intensity expressed as the percentage of the maximum values, no statistically significant differences were found among exercises. Conclusion: Cardiorespiratory responses are directly associated with the muscle mass involved in the exercise. Thus, it is worth emphasizing the importance of performing a maximal test that is specific to the analyzed exercise so the prescription of the intensity can be safer and valid.