According to dictionary.com, "diving" can mean merely the act of being beneath the surface of the water.
Lets take this several ways, why don't we?
I guess this means accidents in swimming pools count as diving accidents, then? When a kid gets under the cover of a covered swimming pool, that counts as overhead, basically the same thing as a cave diving accident, correct?
People who hit their head and drown in their bathtub, that's a diving accident.
People who drive cars into lakes, those are diving accidents. Since they are contained in an overhead environment, once again, we find they have died in what is basically a cave diving accident.
Dictionary.com suggests that a "surface" is the outermost layer of a thing. We all know there is water in the air, and this atmosphere extends up quite a ways. Therefore, the outermost layer of the water is probably several miles up. It could be that we are all technically under the outermost layer of some amount of water for our entire lives--funny, we are technically diving even on our surface intervals, eh?
It's all in how you define something.
Wikipedia defines cave diving as
Wikipedia:
Cave diving is a type of technical diving in which specialized SCUBA equipment is used to enable the exploration of natural or artificial caves which are at least partially filled with water.
Dictionary.com defines a cave diver as one who uses specialized equipment to dive in caves. I doubt goggles would be considered specialized equipment to anyone but cave men.
Cavediving.com makes the distinction that cave divers use specialized equipment in the form of redundant gas delivery systems.
During my time at UCF, someone shot themselves in their car in the parking lot. Was that a car accident? And those people who pipe exhaust into their cars to commit suicide, those are also car accidents?
Yes, she died in a cave. However, this was clearly not a cave diver fatality. Being in a cave does not make you a cave diver, as I've shown through multiple definitions, any more than sleeping in a hangar makes you an airplane