Heroes in training graphic novel. No. 1, Poseidon and the sea of fury / created by Joan Holub & Suzanne Williams ; adapted by David Campiti ; illustrated by Dave Santana at Glass House Graphics.

Enhanced descriptions from Syndetics:

A young Poseidon must triumph over aquatic terrors in this second graphic novel adapted from the popular Heroes in Training series!

The terrible Titans--merciless giants who enjoy snacking on humans--have dominated the earth and driven the world into chaos. But their rule is about to be put to the test as a group of young Olympians discover their powers and prepare to righteously rule the universe...

The terrible Cronus and his Titan buddies are in hot pursuit of Zeus, Hera, and Poseidon, who plan to travel across the treacherous boiling sea to save a fellow Olympian. They have a boat, but they also have a problem: Poseidon can't swim and is terrified of the water (well, really of the creatures that lurk in its depths).

The group faces danger after danger as they battle singing sirens, a fishy and ferocious Titan named Oceanus, and people-eating monsters sent by Cronus himself. Can Poseidon overcome his fears and help his fellow heroes escape Cronus and his cronies?