How could the wreck be shallow enough for sponge divers to reach (no dive gear), and yet be too deep for SCUBA divers? That makes no sense to me. Maybe they were phenomenal divers, who knows?
When I was younger I could free descend to about 75 feet and could hold my breath for 3 minutes, but that was after spending an entire summer, 8 hours a day, swimming.
When I first read about the Antikithera mechanism as a kid, the story was that it was found by “sponge divers”. I pictured a couple kids my age in a rowboat or something, goofing off on a summer day, in ten feet of water.
In those days sponge diving was an industrial affair, with brutal working conditions and a very high mortality rate, because “the bends” wasn’t properly understood, and primitive dive gear.