Snorkling with the Manta Ray's was wonderful! We had floating tubes on ankles and held on with our hands. Most wonderful experience ever! I would trust this particular company:
https://www.seaparadise.com/manta-ray-night-snorkel/
My favorite place to snorkel was Kahalu’u Beach Park. It was amazing watching the various fish and my one turtle. I took a noodle with me as you can’t put your feet down onto the corral. I had a mask and no fins—and I didn’t miss the fins…Mahalo!
I would forgo the expensive kayak trips. Waste of $ and I could have rented kayaks on my own.