Ah, am probably confusing iRiver with iDive! Apologies for that.I know H20 audio had a separate dive product (reviewed here First Look: H2O Audio iDive 300 Deep Dive Waterproof Case + Speakers ). Maybe just a case of different product names for different countries?
They're very rare and have similarly esoteric use cases: deep diving, but not too deep, but enough for hours of deco boredom.