Similar to scuba, Snuba allows you to remain underwater for an extended period. You have limited amount of freedom, about 30 feet of hose. It's quite safe and because it requires little equipment, it's easy to do. Not all resorts offer Snuba diving. The next level is through a resort course.
Resorts offer a one-day scuba diving package for people who have never had any dive training.
The package includes a 30-minute class, diving equipment and two dives in 30 to 40 feet of water. You are not certified or properly trained after this, but hopefully you've had a wonderful experience and are motivated to get certified. However, most certified divers will warn you against the resort dive experience. It can be very dangerous. Get properly trained first.