Complex sentence: In some cases this is a prescribed limit established by an authority, and in others it is associated with a level of certification or training, and it may vary depending on whether the diving is recreational, technical or commercial.
Split into simpler sentences: In some cases this is a prescribed limit established by an authority, and in others it is associated with a level of certification or training. The limit is interpreted in different ways by different authorities and may vary depending on whether the diving is recreational, technical or commercial.