To snorkel you don't need a lot of complicated equipment—a mask, snorkel, fins, and swimsuit or swimming trunks are all you need.
Mask. It's important to buy a good mask that's the right size for your face and has a tight-fitting seal. The easiest way to test how well your mask fits is to lift the strap over the top of the mask and press the mask to your face without breathing in. If it stays tight to your face (without you holding it on), you've got the right fit. If not, keep looking until you find one that seals properly. You'll want to get a mask that has a glass face (not plastic) to keep it from fogging up or making the sites below look weird.
Snorkel. There are many different sizes and designs of snorkels—find one that is comfortable, and allows you to clear water easily. It's important that you find the right snorkel for you—it's what helps you breathe while you're cruising along in the water checking out the sites below.
Fins. There are a few different types of fins to choose from—full-foot fins fit like a slipper around your heel, while open-heel fins fit your feet and have a strap that fits around your heel. Your fins should be snug, but not too tight (if your fins are too tight or loose, they may cause blisters). They should be flexible and lightweight—to give you speed and mobility. You may also want to get diving booties to prevent blisters and protect your feet.
If you're swimming in salty water, make sure to rinse all of your equipment with fresh water. If you don't, salt crystals can form causing the straps to stiffen and crack, and the fabric may tear. So, keep your equipment clean. Remember, it's what allows you to move through the water and check out the underwater world more easily!
Always make sure your snorkel, fins, and mask are in good working order before taking the plunge. It's also important to know the basics like how to clear water from your snorkel (blasting), and how to put your mask back on while treading water. Until you get more experienced, you may want to wear a life jacket—it will help you stay afloat if you need a rest, or if you get into trouble in the water.
Most importantly, never snorkel alone. Always swim with a buddy and keep them close by so you can help each other out—and, it's more fun with a friend!
Use your noggin'—check out the weather forecast and the water's visibility before you jump in. And don't forget, coral reefs are fun to explore, but don't go too close to them until you've learned how to steer your body in the water. Never touch a reef—they are sharp and some have ocean life that may be poisonous. Always be considerate of the places you are snorkeling in, they may be another animal's home.
Finally, watch out for the sun! Wear a t-shirt and sunscreen to make sure you don't get sunburned.