Pharos, Temple of Isis - Level Entrance and Underwater Ruins

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The passageway from the COASTAL RUINS to PHAROS, TEMPLE OF ISIS, is at the southern end of the tide pools, near where you emerge from the HALL OF DEMETRIUS. In the screenshot above, Lara is standing in the area marked "beach" on the map of the ruins, and door E is behind her. Wade out into the water. Just beyond the first rock outcropping on the right side of he pool, dive down...

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...and swim into the underwater passage.

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Follow the passageway forward then left.

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Swim between the jumble of carved blocks and turn left again.

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Swim forward and down to the right to transition from the COASTAL RUINS to the PHAROS level.

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After the new level loads, you'll find yourself in a flooded cavern. The current pulls Lara along, but there's no need to fight it. Just keep swimming forward.

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As you approach the submerged ruins, a hammerhead shark swims out from behind the right side of the building. There's an air pocket in the ceiling with a small ledge on the left where you can climb out of the water and shoot the shark, but this takes time, and you may need to hop in the water to get the shark's attention, climb out, and shoot at it several times in order to kill it. It's probably easier to just head for one of the small, square openings about halfway up the front of the building.

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It doesn't matter which opening you choose first, so we'll head for the left one. Swim inside and climb out of the water. If the shark follows you into the opening, turn around and shoot it, but don't worry if this doesn't happen; you'll have another chance soon.

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Follow the stairs up to dead end and place the PHAROS KNOT in the receptacle.

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Swim back out to the cave, turn left...

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...and swim forward, keeping the building on Lara's left. Then turn left into the other small, square opening.

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Climb out of the water...

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...and place the PHAROS PILLAR in the receptacle there. This opens the carved doors down at the base of the building (not the wooden panel between the two square openings).

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Swim down to the bottom...

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...and through the door...

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...luring the shark inside with you.

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Continue swimming up the flooded steps.

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Once Lara can stand, turn around and use pistols or a single poisoned arrow from the crossbow to kill the shark—or just avoid it and continue into the ruins.

[Pharos Walkthrough]