This reminds me of the Libyan line of death and a Libyan submarine that radioed the beach to say they were diving, waited 20 minutes or so on the surface, and then reported they had resurfaced - all watched and heard by our navy air folks. They were too scared to submerge for fear of never coming back up.
That being said let them sit in their shallow pond while our P-3s locate them with MAD gear and then drop sonobouys all around to ping the living crap out of em - then see if they stick around to light anything off. hmph - plus being diesel they’ll have to surface periodically for crew air.
I will give them that at 500 tons it’s a fairly small boat and harder to ‘see’. Ours tend to be 6000 tons or better as I recall.
Our Carriers about 100,000 tons
The Virginia Class Attack sub about 8000 tons
The Chains/Anchor on our Carriers probably weight nearly 500 tons.
500 ton stealth sub what did it do sink and never come up.
ROFL