Snorkeling isn’t really a dangerous sport or hobby but, as in any sport and in particular water sports certain hazards are apparently built into the hobby. Snorkeling is no different in this respect. There are the normal water sport type hazards one would encounter if you were swimming or diving. Occasionally you might encounter a few situations underwater that make you a bit fearful. The first thing you must realize is do not panic. The best tip for a snorkeling beginner however is not to go alone! Take a buddy with you.

Your mother has probably told you this countless times. Many underwater areas are covered with large coral reefs. These reefs are beautiful to look at however they can present a certain amount of hazards. The different animals that live there, including the corals (coral is a living thing), have bacteria associated with their living and eating. This bacterial, combined with a cut from a sharp coral, can cause very sever health issues. Past the fact that you might kill a very old and living thing, it’s safer to just not touch the reef. The other don’t touch involves fish and snakes. The safest course of action is to look and don’t touch.
Jellyfish, eels, snakes, or even sharks, they are all out there, but in most cases they wont harm you, if they are dangerous at all. But a creature we have to mention here is the sea urchin. Sea urchins are small, dark spherical type creatures with skinny black spines that are two to three inches in length that radiate out in all directions. Their usual spot to congregate is in crevices and upon the rocks and they enjoy feeding upon the algae in the water. The spines of these creatures are extremely sharp while the tip has been known to break sharply and remain uncomfortably embedded in ones skin if you should stumble upon them. These spines contain a form of mild venom which when encountered causes great pain and considerable swelling of the wounds.  
Any time you have a large body of water connecting to the ocean you are bound to encounter a few shark of some sort. Many fishermen occasionally bring in a large quantity of sharks from their day at sea fishing, however in order to do this they must go into the deeper parts of the water and must place bait out to attract these creatures. Most of the sharks found close to the shore where the snorkeling is accomplished are of the smaller variety and rarely bother or present any sort of threat to swimmers.
There are specific time when the ocean and its associated waters would become much too rough to engage in snorkeling. This phenomenon relates to storms (bad weather conditions). A storm doesn’t need to be close by to have an effect upon the oceans, so be sure to check weather prior to going snorkeling and be certain to heed all issued warnings and precautions and you have watched the weather forecast.

The nice warm water and sunshine, in most snorkeling spots, lends itself to becoming dehydrated and tired much quicker than one might think. You are in water you say, how can I become dehydrated? The sun and salt will do their job so drink fluids (not alcohol) and pay attention to your dive watch. You can always snorkel later in the day.
Keeping track of your position is a critical aspect of snorkeling. You may think that you are far enough away from a rocky seashore rock outcropping, but just one or two waves can put you on or against them very quickly. Even worse, if the wave doesn’t put you onto the rocks but merely against them, the next wave and the one after that will continue to hurt you.

Snorkeling spots with tides are another snorkeling hazard. If a rip tide forms, or you have been snorkeling at the change of the tides, you can very easily be drawn out to sea or against the rocks. Keep an eye on where you are at all times.

Learning the simple procedure of cardio pulmonary resuscitation (CPR) saves lives. Not only is learning this skill a part of being a good person, it is a skill that will possibly save a loved one you may be snorkeling with. The class to learn, and be certified in, the skill takes two consecutive nights (in most Red Cross instances) over 8 total hours.