Little is known about the transfer of swimming skills from indoor, flat, calm conditions to outdoor, wavy, unsteady conditions. The aim of the current study was to examine the differences in swimming, floating and entry skills in children between calm and simulated open water conditions. Sixty-six children, 11 years of age, were tested on two occasions, once in calm water and once in simulated open water conditions. Testing consisted of a 200 m time trial, a 3 min back floating test, a diving entry, and a rolling entry. The results show an 8% decrement in performance on the 200 m swim between calm and unsteady conditions for those who completed the 200 m under both conditions. When weaker swimmers, who only completed 50 m of the 200 m test distance were tested, the performance decrement rose to 14%. The diving entry, the rolling entry and the floating test had decrements of 16%, 21%, and 24%, respectively. We concluded that 11-year-olds should not be expected to reproduce swimming skills they have performed in calm water with the same proficiency in unsteady conditions during an emergency.