They stopped calling it Happy Harbor when the water park was built. Once this area was Shamu’s Happy Harbor at SeaWorld of Ohio. The majority of attractions in Wildwater Kingdom were built here, including the water slide tower, Riptide Run, and Coral Cove. The last two were built on top of the Dolphin Cove area.
What may be more interesting is that none of this existed when the park opened in 1970. Other than the area of blue chairs next to the water (the footprint of the old Water Ski Stadium), this was all parking. Even the original entrance was outside of this picture to the bottom right.
Courtesy of Google Maps.