Blood in the Water

Upon boarding the Shinra-8, head to the 2nd Class Cabins. Explore the large rooms for materials and two chests, each containing 2x Antidotes. Be careful not to miss the chest near the side room door.

Proceed to the main lounge. Speak with your party members; Red XIII will not participate in the Queen's Blood Tournament.

On the outside deck where Barret is, find a Fortification Materia on the ground.

Return to the main counter in the lounge and speak to the NPC (non-player character — anyone the game controls, not you) with a marker above their head to sign up for the Queen's Blood Tournament.

Participate in the Queen's Blood Invitational. This is an optional tournament with a trophy for winning. You can retry matches if you lose, with no penalty.

The tournament proceeds in rounds. Your opponents are: Round 1: Felix, Wize; Round 2: Aerith, Barret, Tifa; Round 3: Andrea, Madam M; Round 4: Chadley; Round 5: Regina.

After winning the tournament matches, return to your room. You will be woken up in the middle of the night.

Exit your room and head to the upper floor to find Captain Titov. You will be tasked with fighting fiends on the ship. Your party will be Cloud, Aerith, and Red XIII.

Head to the outside portion of the ship to fight two Scrutineyes, followed by two Experimental Varghidpolis. The Scrutineyes are weak to lightning.

The Experimental Varghidpolis have a countdown; if it finishes, they use Deafening Screech. Stagger them before this occurs. Three more Varghidpolis will appear after the initial two.

After defeating the Varghidpolis, a scene will play, and Cloud will return inside the ship.

Fight two more Scrutineyes, then go through the nearby door to get below deck.

Meet Tifa and help her fight two Varghidpolis.

Run down the hallway to witness a scene and encounter the Necrotic Entity. Pressure it by using powerful offensive abilities while it casts spells, evading its Onslaught skill, or attacking during Subastral Fury.

Continue to the Cargo Hold. You will face another Necrotic Entity and a Daemonic Entity. The Daemonic Entity flinches when attacked from behind and is weak to ice.

Before proceeding, check an alcove to the left of the main path for a purple chest containing the Kaiser Knuckles for Tifa.

Take the main path to another portion of the cargo hold and fight two Daemonic Entities.

Follow the path, duck under debris, and go up the stairs to find a chest with a Mega-Potion.

Just beyond, you will fight one more Necrotic Entity and a Shrieker. The Shrieker can teleport.

In the next room, you will find a resting bench, a vending machine, and a Maghnata Automat. Heal and save your game.

Enter the following room for a cutscene (a non-interactive cinematic the game plays automatically), immediately followed by a boss fight against Jenova Emergent.