Many sources use "recreational" to describe diving with ordinary air (or maybe nitrox), and "technical" any diving with more complicated requirements. Both are distinguished from "professional" diving, so you can be doing "technical" diving recreationally without doing "recreational diving".
Wikipedia says that the exact definition of "technical" varies between certifying agencies, but 50 meters is definitely well below it. You can certainly do it without being certified, but the training classes make it clear that you're taking a massive risk (oxygen toxicity, nitrogen narcosis, decompression sickness).
I've got only the most basic certification myself, and only a short list of dives, so I can't speak to how realistic that is.
Wikipedia says that the exact definition of "technical" varies between certifying agencies, but 50 meters is definitely well below it. You can certainly do it without being certified, but the training classes make it clear that you're taking a massive risk (oxygen toxicity, nitrogen narcosis, decompression sickness).
I've got only the most basic certification myself, and only a short list of dives, so I can't speak to how realistic that is.