I like your criteria, but it seems to apply to whether it's appropriate to refer to as dive as a "scuba dive." Your sentence that gamon referred to began, "You can only log something as a scuba dive if ...." So the sentence also relates to whether a dive "can" be logged. Being a pedant like me, I think you will concede that you have two separate but related assertions in that sentence. While I like your definition of a scuba dive, I will also agree with anyone here who has said there are no restrictions on what a person can log, as a log is simply one's personal record, maintained for one's own benefit. An exception is if the intent of the log is to satisfy some authority such as a dive training agency that may want to see evidence of meeting prerequisites for a course or something like that.Well, I have no source except for myself. Very few things in this world are hard facts. Opinions abound, though. I will explain my reasoning below.