In your scuba course, you'll learn a simple technique to equalize your ears to the surrounding pressure, much like you do when you land in an airplane, and your ears won't hurt at all. The length of time you will be able to stay under water depends on several factors, including how deep the water is. The time for each dive is calculated from Diving Tables. The time for a dive is also dependent on the air supply in your tank. In the Open Water Class, you'll learn how to know how long you can be underwater and how to monitor your air supply.
Statistics show that recreational scuba diving is about as safe as swimming.
Certainly there are potential hazards, which is why you need training and certification. Like driving a car, as long as you follow the rules and use common sense, it's pretty safe. Like any hobby or recreation, you can invest a lot or a little, depending on your interest level. Because most dive centers and resorts rent equipment, you can invest in equipment over time, renting what you don't have until you make the investment. You probably have good diving not too far from where you live, so even travel costs are flexible enough to accommodate even the tightest budget.