The Second Trumpet
One third of the sea turned to blood, a third of the sea creatures died, a third of the ships were destroyed.
The trumpet referred to here was a shofar which is a ram's horn which the Israelites used for religious purposes and for warfare.
Background Reading:
Revelation 8:8-9
The Second Trumpet
8 The second angel sounded his trumpet, and something like a huge mountain, all ablaze, was thrown into the sea. A third of the sea turned into blood, 9 a third of the living creatures in the sea died, and a third of the ships were destroyed.