According to a joint survey by the Themed Entertainment Association and Economic Research Associates, Caribbean Bay attracted 1.4 million visitors last year, ranking third in terms of the number of visitors.
Disneyland's Typhoon Lagoon in the United States ranked first, with over two million visitors, followed by another U.S. waterpark: Blizzard Beach in Miami, with 1.9 million people.
Meanwhile, Korea's three other popular waterparks also made the list.
Ocean World was in 8th place, with 900,000 visitors last year, while Deoksan Spa Castle ranked 11th and Seorak Waterpia 13th.
Everland, where Caribbean Bay is located, consistently ranks as one of the most-visited theme parks in the world. It ranked 10th in the world in attendance in 2006, while Lotte World ranked 15th, according to the information presented in this Korea Times article. According to that article Everland was the fourth-largest park in the region, behind three in Japan.
Google tells me that the Korea Times site "may harm your computer." I blame their Dokdo coverage.
Marginally related, here's a list of "The 9 Most Baffling Theme Parks From Around the World," from Cracked.com. Jeju Loveland came in second; check out number 3.