From the Publisher:

You are a marine researcher seeking to find and observe an array of aquatic life in the colorful Sunlight Zone, ghostly Twilight Zone, and pitch-black Midnight Zone of the world's seas and oceans.

In Finspan, the fish you discover over 4 weeks will generate a series of benefits as you dive deeper into the ocean. The winner is the player with the most points gained from fish, eggs, young, schools, and achievements.