So when you book this, you must cancel 4 days in advance for a refund. I scheduled this in advance for day 3 of our vacation. The weather was not good on the day we went. Rainy, very windy, and high waves. The company does this regardless of the weather. Our experience was not good. The boat was rocking so hard, many people were sick, and while the scuba equipment was cool, we saw nothing under the water. The crew was great, but the company should really look into a better policy for the weather and allow people to cancel if the weather is bad. My advice is to not to book this in advance until you see what the weather is going to be!