They're at "depth pressure", so a small breach would not be an implosion but a dribble of bubbles ascending from the station accompanied by an equal volume drib

They're at "depth pressure", so a small breach would not be an implosion but a dribble of bubbles ascending from the station accompanied by an equal volume dribble of water into the station. If so, they probably have time to employ whatever their normal ascent plan is. If they were at atmospheric pressure, it could be a calamitous, crushing implosion, but if they had warning, 20m down and back up is a fairly straighforward freediving depth (he says, having only accomplished 12m personally). Unfortunately, they're not at atmospheric pressure, they're at 3 bar. Recreational divers can be at this depth for about 35 minutes and then will ascend slowly at about 10 meters per minute. Longer or deeper, and they'd be required to perform decompression stops, which is a whole different, much more dangerous animal: handling emergencies that don't allow immediate ascent changes the risk level from driving a car (just pull over if something goes wrong) to flying an airplane. If you spend an hour at 20 meters, you'd need to pause for about 15 minutes at 3m below the surface (so close! but it's a logarithmic stackup), breathing gently from your SCUBA system at this reduced pressure, waiting for gasses to dissolve safely and slowly out of your bloodstream. None of the dive tables I have access to cover saturation diving, so ascent after more than an hour - after a day, a week, or more - isn't covered. So, assuming they have access to SCUBA gear, they should stop at roughly 9, 6, and 3m from the surface on the way up for increasing amounts of time. All that said, failure to ascend to the surface will eventually be fatal; humans can't breathe seawater. Taking chances with the bends risks air embolisms that may cause a stroke or heart attack and be fatal, but if might not get unlucky; it's worth taking a chance!