Boils the ocean and kills fish

Finally he noticed that dark objects were floating up from under the surface of the bubbling ocean.  The shapes were silhouetted in the blue brilliance.
Fish!
Hundreds of them.  Thousands of them.  Fish of all sizes and shapes.  And they were all dead.
Koh clutched the railing.  His mind reeled.  And then he felt a moist heat against his exposed skin.  Koh sniffed a strange odor.  A rich, salty, briny smell, not unlike fish soup.
“The ocean!” Koh screamed as the realization hit him.  “It’s boiling!”