With the second trumpet a waving flood of fire, great as a burning mountain, was cast in the sea.
Schult (p.146) sees in this falling mountain of flames again the combination of luciferic passion and ahrimanic hardening. The reason why the destruction now concerns the sea is that in his view the astral forces of passion and calculation digest the etheric life forces. This results in the annihilation of the etheric world as well as the life of fish and other water animals. Again one third of life is affected, referring as we saw to the three-fold realm of the remaining world, in which now the etheric is going to be excreted.
Bock associates the falling mountain more explicitly with natural sciences that focus only on the material phenomena and block the view on the world of the spiritual causes.
Dullaart suggests to see these consequences as our challenge to connect our feelings more with the animal kingdom and help safe it.