Big Blue is an ancient Blue Whale, and has witnessed many events of the Earth's history. He is one of the few life forms in the ocean, other than the Asterite, who has knowledge of the Vortex storms without having seen it.
The Big Blue in Ecco the Dolphin was swinming to the arctic to live out the last of his life, and Ecco swam after him in order to learn of his pod's demise. The Big Blue told Ecco of how he has witnessed several of the storms in his time, storms which drain the ocean of all its life forms in the afflicted areas. Big Blue informed Ecco that there was no more he could tell him, and to seek out the mythical Asterite; the only being who could possibly know more than himself.