Do you need to be certified in scuba diving in order to go diving?

[Just Me]

My husband and I are interested in scuba diving when we take a trip to Florida. Although we are both good swimmers and frequently snorkel, we have never tried scuba diving. We have looked in to taking classes and they are very pricey. To get certified in our city, it will cost us $500 and that does not include equipment. I think it is a little pricey especially since we might shell out all the money and not enjoy it as much as snorkeling. I see scuba diving excursions in Florida all the time, do you have to be certified to go on a beginner dive? Can we take a dive excursion that offers not certification but a quick beginner lesson before going out? My husbands ready to sign up for the certification classes but I'd prefer to try it out first. Any advice appreciated