19 Or “a third of the living creatures in the sea”; Grk “the third of the creatures which were in the sea, the ones having life.”
20 On the term translated “completely destroyed,” L&N 20.40 states, “to cause the complete destruction of someone or something—‘to destroy utterly.’ τὸ τρίτον τῶν πλοίων διεφθάρησαν ‘a third of the ships were completely destroyed’ Re 8:9.”

In other versions

A third of the living creatures in the sea died, and a third of the ships were destroyed.

a third of the living creatures in the sea died, and a third of the ships were destroyed.

a third of the living creatures in the sea died, and a third of the ships were destroyed.

one-third of all things living in the sea died, and one-third of all the ships on the sea were destroyed.

and a third of the creatures in the sea—the ones which had life—died, and a third of the ships were destroyed.

And the third part of the creatures which were in the sea, and had life, died; and the third part of the ships were destroyed.

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