We had high hopes for this experience based on all of the reviews out there, but in the end, we were disappointed with our trip. We didn't see very many manta rays, they didn't get very close, and we spent a long time lying face down in dark, chilly water hoping to see more. My wife was hit with pretty severe sea sickness from bobbing in the water (not from the boat ride, which is very short), and three of our four family members were very cold despite the wet suits provided. We went snorkeling ourselves at the Captain Cook monument and at Two Step and both were 10x better experiences that didn't cost a penny.
It is important to note that Sea Quest Hawaii did a really good job with everything that was under their control. They are a professional operation and their employees did a great job.