From the book:
The mighty seas and oceans are more than just a color on the map. Lurking just below the surface of those waters are civilizations and dangers that landed folk can only whisper of in children’s fables. Those stories are a reality, but only true adventurers get to see the stories come to life before their very eyes.
Those that claim to understand the magnificence and power of Nature must also include the waters of their realm. Survival techniques, terrain features, the dangers that lurk in the depths, civilizations, and creatures are just some elements of essential lore that bards, druids, rangers, and others should grasp.
For the GM, Into the Blue allows the waters of a world to churn with as much life as the mountains of the dwarves or the forests of the elves. Take your adventures to the next level among the kelp jungles and deepwater trenches of the oceans.