Cook Islands Business Directory: COK is the ISO 3 alphabet country code of Cook Islands. Currency of Cook Islands is $, which has a short code of NZD. Capital of Cook Islands is Avarua. Cook Islands has the population of 17411 and approximate area is 236.00 square kilometers (or approx. 146.6504 square miles). Population density of Cook Islands is approx. 73/Km2 (or approx. 45.3622/mile2)