Kamehameha County Park. This is a park that's open to the publica and offers free sports and swimming areas to anyone wanting them. You are also encouraged to picnic here. Keokea Beach Park. This is quite an amazing beach that you certainly won't want to miss.
Few people use the beach during the week, but it's a popular retreat for the locals on the island.
This is not a good swimming location, because of the rocky shores, but is a great place to hang out in a nice beach area. This is the area that used to be a Kohala Girls School. This was once a missionary estate and is preserved by the Bond Family. You can tour the home here or just the grounds. This is a great place to learn about the rich history of the area.