This is the video Jelly Fish All Around.
Its makers explain:
“The jelly fish came to this lake in Palau through a tunnel which connected the sea and the lake long time ago.
Now the tunnel have closed, and the jelly fish came to have no poison in an environment where there’s no predator.
They live by photosynthesis because they cannot feed on anything in this lake. This lake is such a heaven to them that there are just so many of them living here.”
Also on Palau here.
Mauve stinger jellyfish: here.
The presence of the mauve stinger jellyfish (Pelagia noctiluca) has been confirmed off the North West coast of Mull: here.
Invasive Australian jellyfish, Phyllorhiza punctata, in Gulf of Mexico: here.