Diver

The Diver is the primary bot and main antagonist of Chapter 4, more over known as the Aquarium. Like Guesty, Papa Guesty, Guest 666, Guest 404, and Guest 777, he was a guest, proven by the standard Guest cap he wears on his head. He could have been purchased as the Diver Bundle for 799 Robux along with the Poseidon Melee and the Bubbles Effect before it went off-sale.

History
Not much is known about Diver, except he worked at the Aquarium prior to the outbreak, possibly catching fish due to his outfit for the Aquarium. When the banwave of Guests started, Diver disappeared like Guesty, Papa Guesty, and Guest 404, but was reanimated to be a monster with hostile intentions like the others. It is possible Diver could have been Guest 777, as it is shown in the ending of Chapter 6 of Guest 777 and Guest 666 fishing, with Diver's helmet on the docks.

Appearance
Diver is a Guest, proven by the Red Roblox Cap all current Guests wear on his head. He wears a Ghost Diver hat, plus a suit, possibly using it to catch fish for the Aquarium. Like the other antagonists with the exception of Gentle Heart, Telamon, and Matt Dusek, his ribs are exposed and his left arm is missing. His skull is also shown, but it can only be seen when scrolling the camera into Diver's head.

His playable character doesn't show much of a difference to its Bot counterpart.

Trivia

 * Guest 777 is implied to be the Diver skin. There is some proof to this, such as:
 * The Diver is confirmed to be a Guest, shown by his Guest cap.
 * Guest 777 owns the Diver helmet, as shown in Chapter 6.
 * For a long time, it was assumed that Guest 777 was TLG (The Last Guest) but in the Secret Ending, we can see Bobby was a Guest too, his parents bypassed the chat filter just like Guest 666, and he was never affected by the Ban Hammer. This means that it is more likely Bobby is the Last Guest, as opposed to Guest 777.