Best playground for kids of all ages-Kamakana Playground
This is a giant playground in the Kona area. There is a fenced structured area for little ones. The large wooden castle with slides is many kids' favorites. There are many types of equipment for kids to play and even has a built-in chessboard. The park also has tennis courts, a basketball, and baseball field, large field to play sports.
This is the coolest playground on the island and not only do kids love it, but it's also a relaxing place for adults as well. The park has an amazing ocean view with several picnic/bbq areas and lots of shades. Nice place to watch the sunset.
Good hands-on experience with Seahorse-Ocean Rider Seahorse farm
Personally, I think it's a bit pricy for the little tour( $63 for kids and $73 for adults) but I think this is definitely a good cause to give your money to. You can book your tickets on their website: Ocean Rider
The tour is about 1.5-2 hours long. The tour is very informative and a great learning experience. You get to put your hands in the water and let a seahorse curl around your finger. For kids, it's a great opportunity to learn a little about marine biology and conservation.
Good hands-on experience with Octopus-Kanaloa Octopus Farm
A bit cheaper ( $40 for children and $50 for adults), you get to play with Octopus at the octopus farm. You learn about the Octopus' behavior and life cycle. There are more opportunities on this tour to play with Octopus than on the Seashore tour and less talking by the guide.
Beaches for kids or less confident swimmers
There are several beaches that are particularly suitable for children or less confident swimmers like me. Check out my previous article Top 4 kids-friendly beach in Kona