Diving is a comfortable, fun and safe activity, provided you are in good health and you stick to the rules. It is this “sticking to the rules” part that requires you to know that you are doing. This is why virtually every diving course has requirements for theory knowledge.
There are only few rules for beginning divers who always dive with a guide. For autonomous divers, the number of rules is more substantial. It does not stop there. When you expand your horizon to go diving in different circumstances or participate in a new underwater activity, there are always new rules – for diving at night, at greater depth, under ice, for taking pictures under water, for salvaging lost objects and so on.
The textbook that provides you with the knowledge and understanding that is needed for beginning divers, and for expanding your horizon, is available on this internet page. Select your level of training (beginner, continuing education or becoming a professional yourself) and then specify your specific wishes. This then brings you to the page where you can start your course immediately.
If you are yourself a diving instructor, but not yet SCUBA C&P qualified, then you go to the page on that subject.
You can also use the shortcut to the course of your choice in the menu to the right (or below if you are reading this on a small screen).