Take the kids on an adventure to experience sharks in the open ocean. Here's what North Shore Shark Adventures has to say about the experience:
Shark encounters on Hawaii are safe, fun, and exhilarating. Fun for the whole family! Some have a huge fear of sharks, but once you are in the shark cage and diving with these sharks you realize how graceful these guys are.
Just in case ... get sea sickness pills for everyone. The pills for the adults and children will be different. Read the instructions on the boxes. Make sure you take them far enough in advance so you and your crew won't experience any sickness.
Last Bit of Advice
If you have a GoPro, you have to bring it. GoPro's are lousy at long range shots, so concentrate on the kids and try to get the sharks swimming in the background.
Be sure to lick the lens cover of the GoPro's waterproof housing. That will stop water from beading up on the lens cover if you are taking photos both in and out of the water.