The flag of the Cook Islands, officially known as the Cook Islands Ensign, is based on the traditional design for former British colonies in the Pacific region. It is a blue ensign containing the Union Flag in the upper left, and on the right, fifteen stars in a ring. The Union Flag is symbolic of the nation’s historic ties to the United Kingdom and to the Commonwealth of Nations.
Link: https://en.wikipedia.org/wiki/Flag_of_the_Cook_Islands