Weather
Strong waves and rain will often cause waters to cloud at shallow depths. With any sign of lighting you should be out of the water. Water, as you know, conducts electricity and lighting is attracted to the tank attached to your back. Diving during strong waves or a hurricane is extremely dangerous, as you could be pushed into coral or other divers.
In light rain in open water though, it may not matter. Even during the rain the fish stick around. It isn’t ideal and the sun won’t be there to comfort you when you get back on the boat, but it can be a great way to save a cloudy day.
Water Temperature
Water temperature is an incredibly important factor when diving. Not only does temperature decrease as you change latitude, but also as you change depths. Wet suits or dry suits need to be worn during dives as your body cannot handle the extreme temperatures.
Safety
Emergency situations do occur while diving on a more frequent basis than many activities. You can touch a poisonous fish or coral, your air tank might not function properly, and you could hit your head on a rock or boat. Generally these are not serious situations, unless you are diving alone. You should always dive with someone else, particularly someone who is a certified rescue diver, which all certified instructors are. It may save your life. Most dive accidents occur from careless preparation and from horseplay, so keep that in mind when trying to show off.
Food and Water
You should eat at least two hours before diving. Go for complex carbohydrates such as fruits, yogurt, and whole grains. You should avoid fatty foods such as hamburgers, French fries, and sausages. Drinking water before and between dives is important as well.
Length of Dives
The length of your dive depends on the amount of air in your tank, which is affected by how quickly you breathe. The quicker you breathe the faster you will run out of air. Many divers will go through one tank, climb back on the back on the boat and rest for a while, and then strap on a different tank.
Medical Issues
Inner Ear problems
Often times your ears begin to hurt when diving to the bottom of a pool. Changing depths puts added pressure on your inner ear and you must adjust by blowing air out of your nose and other techniques that an instructor will show you. If you have a history of inner ear problems, you should consult with a doctor before diving.
Sun Protection
Considering you will be out on a boat and in the water, where the suns rays are reflected back onto your body and eyes, Sunscreen and sunglasses that absorb at least 90 percent of UV sunlight are important.
Dehydration
Dehydration is a common ailment of divers. Your body needs water and when you are doing any sport you will go through plenty of it whether you realize it our not.
Hypothermia
Diving in cold weather and at significant depths is a common cause of hypothermia, which is why the correct wet or dry suit is so important.