Is clearing water from a mask an example of something you need to know in order to be scuba diving certified ?
Basic diving theory : * Diving physics * SCUBA Equipment * Human physiology * Diving hazards and precautions * Diving signals * Buddy system Basic water skills : * Finning and mobility in-water * Fitting and wearing a diving mask * Snorkeling * Shallow free - diving * Entering and exiting the water ( seated entry , ladder exit , giant step entry , etc. )