Ground penetrating radar.
Metal detectors
Underwater drones with mini torpedoes.
Drag the half-sunken Iran Naval ships back and forth.
Huge fishing nets dragged by trawlers.
Neodymium magnets , picks up 2500 pounds, sells for less than $10 on TEMU. Took me 30 minutes to pry mine off a steel I-beam.
There are all kinds of methods to find and remove underwater mines, IMHO.
We have some of the best submarine detection capability in the world, if not the best. But of course, somehow, we can’t figure out mine detection.
Honestly you have to remove part of your brain to believe some of this claptrap.