Scene summaries may contain spoilers
You enter the tunnels which lead under the sea from the mainland to Tomorrow Island. You are warned to keep your t-shirts on in order to avoid the "annihilation protocols". Dr. Tomorrow points out the luminescent eels who light your progress through the glass tunnels.
Entering the underwater observation bays, you encounter a man called Titus Irving, who has been hiding there for a long time, surviving on peanuts. You decide to get him back to the mainland before pressing on, but must first recover his survival kit from a separate section of the tunnels. Your connection with Sam cuts out as you get deeper underwater.
You collect the survival kit for Irving, who draws your attention to a new hybrid - an orca crossed with a bat. A mysterious sonar pulse begins to sound, and the orca begins to attack the tunnel. You flee.
You shelter from the orca's attack, but you won't be safe for long. The deadly jelectric eels are entering the tunnels through the cracks created by the orca. Maxine gets stung by an adolescent eel before you flee, directed by a mysterious voice coming over the loudspeakers, and protected by Irving, who holds the eels off with buckshot.
You flee into the crew tunnels to escape the jelectric eels, moments before the visitors' tunnel you left collapses, removing any hope of Irving returning to the mainland. The breach in the tunnels triggers an annihilation procedure, and you are warned to evacuate.
You escape the tunnels, arriving on Tomorrow Island. You are still unable to raise Sam on comms. Dr. Tomorrow makes contact with the woman you heard on the loudspeakers, Evelyn, who warns you all about the dangers of the island. Evelyn tells you all to get some sleep - tomorrow you'll need to make your way across the island to the boat on the other side in order to escape.