Habituation of the cold shock response, and adaptation in deep body cooling with prolonged cold water immersion is well documented in adults. This study aimed to determine whether children exhibit similar responses. Eight children aged 10-11 years underwent a 5 min static immersion in 15°C (59°F) water, five then swam for up to 40 minutes, before and after a year of regular cold water swim training. Following acclimatization, no differences were found in heart rates or respiratory frequencies on initial immersion, despite a smaller relative VO2. Children reported feeling warmer (p < .01) and more comfortable (p < .05), implying acclimatization of subjective perception of cold. No difference was found in cooling rates while swimming. On comparison with data of adults swimming in 12°C (36°F) water, no difference was found in cooling rates, but the trend in both acclimatized groups to a slower rate of cooling was significant (p < .026) when the data were pooled. These data may support a theory of insulative adaptation.