Scuba diving is a thrill. I love it! It is an activity that I enjoy with my wife. It is yet another way for us to get out and see the world, and to see part of the world most people never see. That said it is not for everyone. Some struggle with clearing ears, some struggle with claustrophobia, some can’t handle the skills, some struggle with general anxiety. I purchased most of my dive equipment used from people to “knew” they would love it, purchased all the gear and then gave up after the pool session, open water session, or after their one and only trip.
A single day course will not certify you. A single day course will not make you a diver. But it will get you wet. You’ll know if you should sign up for the next PADI course and start buying equipment, or if you should stick with snorkeling.
If you’re trying the one day course, make sure the divemaster will be with you on your open water excursion. Make sure you are confident in your own limited skills and in the professional skills of the divemaster.