The Pit

Run up to the top. On your right, you'll find an alcove with a little ghost-attracting statue. Jump there and turn around. Jump at the ladder and climb down. There you'll find a deep pit in the middle and four drains leading towards it. Alas, the water is turned off, so you can't get down into the pit.

The Chamber North

Enter the passage on the north side, that's the one behind you on the right if you come down the ladder. Follow the passage. Shoot the two skeletons waiting for you around the first corner. You'll come to a room with a pit. Enter the passage on the other side. Crawl into the gap. Climb out on the other side. Shoot the vases ahead and collect the Uzi Ammo. Step towards the archway on the right. The black holes on the ground indicate fire traps. Avoid them. Jump over to the vases. Shoot them and pick up the crossbow ammo. Now quickly turn around and shoot the two skeletons. Then collect the blue and red shotgun ammo. Now return to the passage. Jump towards the Poseidon Statue and use the next trident. Run back along the passage and jump into the water. Dive ahead and climb out on the other side. Cross the room with the pool and follow the passage on the other side. Return to the pit.

The Chamber East

Enter the passage east, that's the one left of the entrance. Run along the passage. In the left corner, you'll find a ladder leading up. At the top, leave the ladder with a backsault or climb off to the left. Run along the passage towards the Poseidon Statue. Shoot the skeleton and pick up the blue shotgun ammo. Now jump onto the pillar with the statue and press action to place one of the tridents on its pole. Run back along the passage and jump onto the ladder. Climb back down. The water is now flowing. You'll be followed by an Air Wraith. Run back towards the pit in the middle and turn right. Climb back up the ladder in the right corner and leave it with a backsault. You're now in front of the little cross statue. The ghost will disappear after a while. Climb back down.

The Chamber South

Now enter the chamber south, the one opposite the wall with the ladder. Follow the passage. You'll come to a chamber with a pole. Climb up. Leave it with a backsault. Enter the passage. On the left is a skeleton lying on the ground. Shoot the vases on the right and collect the blue shotgun and the crossbow ammo. Now run towards the Poseidon Statue. Shoot the skeleton, then use the next trident. Shoot the remaining skeleton on your way back. Jump onto the pole and slide down again. Return to the pit by swimming and walking through the stream.

The Chamber West

Now enter the chamber on the west side. In the left corner, you'll see an opening and a black hole on the ground. This is a firetrap so you have to be very careful. Step towards the wall left of the firetrap and carefully approach sidestepping to the right. Jump up and grab the ledge. Crawl into the passage. Run along the passage and shoot the vase on the right to find a Small Medipack. Now use the trident on the statue. Shoot the three skeletons on your way back. Crawl into the passage turn around and hang from the ledge. Shimmy to the left as far as you can. Then let go. If you catch fire, jump into the water and make a roll. Return to the pit once more.

Into the pit

Now that all four streams are activated, you can jump into the pit in the middle. Dive down into the passage and deeper down. Follow the small tunnel. You'll come to a little pool. Climb out. Run up one of the passages ahead and shoot the skeleton. Turn left and run further up the stairs.

Ghosts

Drop down into the next room. Two Air Wraiths will appear. Shoot the two vases on either side to reveal the cross statues. Wait for the ghosts to be destroyed. (If you press the button on the left, a trapdoor on the opposite side will open. The passage leads back to the Coastal Ruins. I recommend going there and opening the door, just in case you forget something and have to come back.) Now enter the chamber ahead. Open the crypt to find the Left Gauntlet. The doors to the passage behind will open. Step inside and crawl into the gap in the middle. Follow the passage.