Alarming levels of human-made debris in Mediterranean sea caves

[alanw]

https://phys.org/news/2025-12-hidden-threats-dark-alarming-human.html

[Cyprus]
In a study published in Marine Pollution Bulletin, we uncovered alarming levels of plastic and other marine debris hidden deep inside Mediterranean sea caves—coastal chambers that also serve as critical refuges for the endangered Mediterranean monk seal (Monachus monachus).
...

Unlike beaches, where debris can accumulate and then be washed away, semi-submerged sea caves tend to trap floating litter that enters but cannot leave.

 

[Cantclimbtom]

Am I being especially thick... how does floaty stuff get in but not be able to get out in a semi submerged sea cave in the Mediterranean?

And what is semi submerged, I assume this means you need to dive to get in? Almost completely all of the Med has tidal range <10cm and most of it <5cm. So can't be a tidal thing unless this cave entrance is just at that exact height around the tide?

I enjoyed visiting one in the Aegean in the summer, but it was particularly nice and very frequently visited, so any litter would be removed asap. It was spotless, maybe not a great comparison to this horribly littered example.

 

[mikem]

Semi-submerged has water in the entrance, but beach at the back - grey seals use similar sites here. It also says that the worst spots are those which face into the prevailing wind / waves.