The scubadiving depth record seems to be around 2300'

Useful link, Faldage. Thank you.

But somewhat self-defeating if you are defending the use of "scubadiving", is it not?

The title at the top of the page you linked us to reads "SCUBA Depth Record".

The "diving", in "Scuba-diving", probably dates to a time when the sport was young. Rather like "horseless carriage" which eventually became "car".