DeepDragon is the boss of DeepDive. He appears near the bottom right of the area, and is accessed through a ship called the "S.S. Eternity".
At the beginning of the first phase and after his beam attack in all of the following phases, DeepDragon will shoot several ice shots while moving his head up and down. He will shoot the shots anticipating where the player will be when the shots reach them, so the divebomb can be useful in avoiding being hit. After he is done firing the shots, he will pause for a second and the third segment down from his head will lose its spikes and become vulnerable. The player must jump over his head, divebomb onto the exposed piece, and hold up to jump back over his head.
After this has happened, DeepDragon will start charging his beam to shoot at the player. Similarly to the ice shots, he will move his head up and down and the beam from his head will damage the player if it is pointed at them. During this attack, the player must hide underneath the overhang created by the first segment below the dragon's head, where the beam cannot reach them. The speed of the dragon's attacks increases along with the number of phases the player has passed.