It feels like some sort of retribution for Moby Richard (I shall call him Richard from here on in, in the interests of decency). He's getting his own back on the bad bastards who would seek to end him.
He's just a nice, hungry whale who wants to breath and eat. You can duck and dive and launch yourself into the air... you can grow and grow and eat sealife and seafarers alike.
Use the mouse to move around, and click to boost.
Don't rush in or you will die... keep an eye on the health tokens and get them when you need them.