Disappearing Fairleads and Bullrings turn 180 degrees
so as they are flush with deck

Older subs have fixed deck bollards but more modern have retractable bollards to take them level with the shell. Example instructions of mooring a sub. Far more sophisticated than a normal ship.
https://apps.dtic.mil/dtic/tr/fulltext/u2/a487311.pdf

@becky....how do you think they moor alongside a quay ?????

1st law of submarine design. As few aperatures as possible. So no

Yes, that is correct @Igor.

As I seen in Kronshtadt they are using mooring buoys for submarines.

They secure using the cables.

Marc thankf for yr comment.
@Brett, MattB, Jim - no idea how they anchored, it was far away. But on next morning did I found about 3 cables behind us another submarine, anchored at St Petersburg anchorage 4A together with merchant vsls.
Recently uploaded http://www.shipspotting.com/gallery/photo.php?lid=3322717

Me neither, but if you read the description above, it says 'at anchor'. I gather what Igor means however.

Never seen an anchor on a sub-TOOOOO risky

When subs launch their ICBM's, doo they check for any vessels on the surface?

How do subs anchor ?

Congratulation Igor for this interesting shot!