The Aquarium — Sharks & the Control Room

Push the crates into the water to make a path across, then continue through the door — the whole facility beyond is flooded.

Head left to the corner door, staying out of the water once you're clear of it, and go straight there without exploring side paths. Climb the stairs and use the Control Room Key on the door at the top — discard the key afterward, it won't open anything else.

Downstairs in the Aquarium Control Room, grab the First Aid Kit and the Aquarium Map. A document on the desk lists a number for releasing tank pressure — the exact digits are randomized per save file, so read it yourself and remember it; you'll need it in a moment.

Through the back door is a storage area with two exits. The first holds grenades — grab them. Take the double doors beyond for the second exit.

Two sharks are dying here now that the water's gone — shoot the smaller one, then head to the back where the giant shark, Neptune, is stranded but not yet a threat. Cross the wet section and climb up; in the far corner, try to grab a key and Neptune will thrash and knock it away.

Head back up through the Control Room and cross to the section of the aquarium the sharks used to block. Shoot the third shark, then take the left door to find Plant 42's roots poking through the wall — they can't hurt you here. There's nothing to do yet, but remember this spot; you'll return once you're carrying something that can put the plant down for good.

Return to the storage room and open the other gate — the water's fully drained now, so this is your only way back. Grab the Magnum Ammo on some crates, head upstairs, and cross back through the aquarium facility to the Guesthouse hallway. Use the Gallery Key on the door marked "Gallery."

Move quickly inside — moths will swarm you here. Head to the back, then left, to find a body; take the Insecticide beside it and backtrack to the hole in the corridor you were told to leave alone earlier. Spraying it there clears the moths out for good, so return to the Gallery.

With the moths gone, take the handgun magazine from the center display case, then grab the Room 003 Key and a red herb near the body you found. Use the key on the door marked "003" and discard it once inside. On the bookshelf, take the Blank Book — instructions for destroying Plant 42 — and check the bathroom, where uncovering the tub yields a dagger. Deposit spare items at the save room and pick up the Red Book left there before continuing.

Back in the Gallery, open the left-hand door. The puzzle here depends on the pool balls you memorized in the Recreation Room: pressing each eye lights up a color that corresponds to one of those balls. Match them correctly to proceed into a small chemical storage room, where you'll find several empty bottles.

Water + Yellow-6           = Green UMB No.4
Water + Red UMB No.3       = Purple NP-004
Purple + Yellow            = Orange UMB No.10
Orange + Green              = Blue VP-017
Blue + Red                  = Brown / V-JOLT

Brewing V-Jolt here changes how the coming boss fight plays out — you don't have to make it, but it's worth the detour.

Take the Red Book and your best firepower, then head back to the aquarium door where Plant 42's roots were harmless earlier. Pour the V-Jolt on them there to soften up the boss ahead of time.

Return to Room 003 and use the Red Book on the bookshelf, arranging its pieces in the correct order. A wardrobe slides aside to reveal a hidden passage into a small vestibule — where Plant 42 itself is waiting.

Head to the fireplace and take the Helmet Key. Barry suggests splitting up again. On your way out of the Gallery, you run into Wesker, who warns you that Barry's been acting strange and that you should be careful — then the two of you separate once more.

Head back through the garden — two dogs wait near the small elevator, so clear them before you climb up — and make your way back to the mansion grounds.

Back at the shed, you find a note from Barry: he's left you supplies to deal with "that bullet-proof thing chained up," and mentions he's fixed the door with the failing handle. Take what he left before moving on.

Open the door and cross the Covered Passage. A new enemy, Hunter Alpha, attacks as you enter — its Grenade Launcher (Acid rounds work best) or Shotgun will drop it, though the Grenade Launcher gives you far more margin for error. More Hunters wait past the door you fixed earlier; clear them and head to your item box.