This walkthrough is meant as a general guide only. It may not include every pickup or secret. There may also be alternative ways of approaching situations within the game.
The level begins with Lara seemingly trapped in a steel and concrete storage compartment accompanied by some calming music and a nice flyby of the area beyond. Turn right and pull the block out once. Head to one side and push block once. Enter the corridor, turn right, then left and enter the alcove on right. Turn around, jump up and grab the jump switch on the inner wall. Exit right, turn right again and pickup the flares and small medipack at the end. Exit right and head straight down the corridor to the end. Pull the block as far as possible (6 times) without blocking your way out. Turn left and follow corridor right past the entrance at the beginning. Keep going forward (east), turn right, then left into another alcove. Jump up and grab the edge of the crawlspace above and pull up. Enter a nicely coloured green room, step on pressure pad in middle and watch cutscene of new door opening. Pickup flares in the far left hand corner. Exit, turn left (south) and follow the corridor as it curves. Head to the south/east corner and pull the block with the horizontal lines out twice. Turn around and enter the newly opened alcove on the left. Push the block once and pickup a Key. Exit left, push the block at the end out of the way and turn right. Follow corridor right, past the entrance at the beginning and right again to the end where there is a key receptacle. Place the key, opening a gate in another area. Exit, turn left and push the block three times until you can access the upper alcove on the right. Climb the block and shoot the grates and enter the crawlspace. You now have a choice to go either left or right.
Secret #0: Crawl right, avoiding the steam to take you to Secret #0... smile and exit the way you came.
Crawl left through the corridor, avoiding the steam and flames along the way. At the end, turn around and grab the edge. Let go and quickly grab the edge of the ledge below. Shimmy around to opposite side and pickup Revolver in the darkened alcove. Drop into the ocean below. Pull up and kill 3 sharks lurking in the water. Pickup the flares on the ledge and dive back into water. Swim south/west and into a hole in the ocean floor.
Secret #1: Swim left to the end of the corridor into Secret #1. Pickup the Uzi ammo, small medipack and Revolver ammo. Reverse roll, follow the right wall out of the maze and surface for air in the ocean.
Swim back down into the hole in the ocean floor. Follow the right wall and make a sharp turn right into another corridor. Swim forward until you reach a wall and turn right. Swim forward until you reach a wall and turn left. Swim through the circular blades and turn left. Pull the underwater lever and a cutscene shows a gate opening in the maze. Reverse roll and turn right. Swim back through the circular blades and swim right. Swim forward until you hit a semi-wall and turn right (see screenshot). Swim through an entrance in the west wall. Follow the right wall and surface in an air hole at the end of the corridor. Turn around and swim out of the corridor following the right wall. Swim through the blades (south), turn right at the wall and follow the corridor left to surface in a new room.
Secret #2: Pull up onto the north/west corner and crawl into the darkened crawlspace into Secret #2. Light a flare, pickup the flares and large medipack and exit.
Enter the alcove in the south wall and watch a cutscene of what lies ahead accompanied by an awesome music segment. Drop down to the slope, head to the north/east corner of the room and pickup the flares. Crawl through the darkened crawlspace in the south/east corner of the room. Make your way around the ledge and jump up and grab the monkey swing. Swing over towards the spiked column until you hear the "watch for danger" sound. Turn around and swing a few swings forward and drop onto the column where the spikes have now retracted. Pickup the small medipack and safety drop to the ground. Jump up and grab the four jump switches on the centre column jumping to avoid the Hammer God as you go along. Take a running jump to the newly raised block in the lava at the east wall. Take a running jump and grab to the rope. Swing, jump and grab the crevice ahead and shimmy left. Pull up and crawl through to the edge of the pool.
Secret #3 (Mini Side Quest): Take a running jump and grab the rope. Swing, jump and grab the edge of the alcove in the south/east corner of the room. At the end of the corridor, climb down the ladder and head to the east wall. Climb up the ladder and pull up into Secret #3. Pickup the flares, small medipack and 2 Uzi ammo and exit. Climb down the ladder and back up the other on the north wall. Drop into the pool and swim under the ledge. Pickup the 2 Uzi ammo and climb out of the water. Take a running jump and grab the rope. Swing and grab the crevice in the west wall. Pull up and climb the ladder back to the Hammer God Atrium.
Use the monkey swing and drop to the centre column. Face east and safety drop to the ground. Reverse roll and take a running jump and grab to the entrance in the west wall. Walk to the bottom of the slope and stop, noting the boulders on the slope ahead. Take two steps forward (see screenshot 1) reverse roll and immediately run forward. Take a running jump back to the Hammer God platform and the boulder falls into the lava below. Immediately reverse roll and take a running jump and grab back to the entrance. [Alternate method (as suggested by the author): Start standing at the right wall, run diagonally (as close as possible to the corner of the square with the spikes) towards the left wall (first ball rolls), sharp turn to the right while 2nd ball starts rolling and you get through between the 2 balls - because the 2nd one starts rolling later than the 1st.] In any case, the slope is now safe so head up the right side to the top. Take a running jump and grab (to change trajectory) to the spikes in the far right corner (see screenshot 2) and they retract (see screenshot 3). Drop into the water on the right, swim through the corridor and up to surface in a new room. Push the floor lever and watch a cutscene of a room now flooded with water. Climb into the crawlspace in the north/east corner and drop into the water back into a previous room. Enter the alcove in the south wall, drop down to the slope. Crawl through the crawlspace back to the Hammer God Atrium. Use the monkey swing and drop to the centre column. Face south and safety drop to the ground. Reverse roll and take a running jump and grab the entrance in the north wall.
Arm weapons and enter the corridor. Turn right and climb the slope. Shoot the Griffin that emerges from the room beyond. Take a running jump to the column and shoot the bats lurking in the darkness ahead. Turn left and take a running jump and grab the crevice in the north wall. Shimmy right until you can pull up into a small area. Arm weapons and shoot the pesky bat that's been nibbling away at your feet. Pickup the 2 Uzi ammo and Uzis in the crawlspace. Crawl back out to the ledge and continue to shimmy right around the corner until you reach a sloped block. Pull up onto the slope, jump, reverse roll and grab the column behind. Arm weapons shoot the Griffin that is trying to push you into the abyss. Take a running jump and grab to the crevice in the south wall. Pull into the crawlspace and crawl through until you can stand. Arm weapons and shoot the 2 small spiders. Shoot the large spider and climb the ladder on the right. At the top, backflip to the ledge, arm weapons and shoot the large spider. Pickup the flares in the alcove and shoot the 2 small spiders in the corridor. Approach the entrance on the right but do not enter. Wait for the floor blades to pass over and run into the room. Pickup the Broken Heart 1 on the block. Drop to the other side of the block, pickup the large medipack and exit. Turn right, grab the pole at the end of the corridor and slide down. Safety drop to the lower corridor, back to the Hammer God Atrium.
Head forward and take a running jump and grab to the entrance in the south wall. Drop into the water at the end of the corridor, pickup the large medipack under the platform and surface.
Timed Run/Circular Blades: Pull up onto the platform and the gate ahead opens. Climb the green block with engraved symbols and another interior gate opens but is timed. Take a running jump and grab (to change trajectory) into the opened entrance. Time a running jump through the circular blades and follow the corridor around. Jump over the beige pad to avoid activating the spiked tile ahead and run through the gate before it closes. Pickup the Broken Heart 2 on the block. Drop to the other side of the block, pickup the Uzi ammo and exit. Now you can take your time back through the spikes and circular blades to exit the room. Take a running jump out of the corridor, back to the Hammer God platform.
Turn right and take a running jump to the raised block in the lava by the east wall. Take a running jump and grab to the rope. Swing, jump and grab the crevice ahead and shimmy left. Pull up and crawl through to the edge of the pool. Take a running jump and grab the rope. Angle right and swing to the south/east corner of the room. Jump and grab the edge of the alcove and drop into the water at the end of the corridor. Swim and pull up into the entrance on the opposite side. Turn left and take a running jump and grab the rope. Angle left, swing and jump to the left side of the slope. Take a standing jump to the next block on the left and angle to face north/east (see screenshot). Take a running jump to the block ahead and with the up and right arrow depressed, take another running jump to the next block. Still holding onto the up and right arrow, take another running jump and curve to the next block. As you've probably noticed, a fire wraith has materialized in the middle of all of this. So without delay, turn to face east and take a running jump to the next block. Take a final running jump to the alcove in the wall and run through the newly opened gate. Follow the corridor and drop into the water to extinguish the wraith following you. Combine the two Heart pieces and place the Demon Heart into the receptacle. Head through the newly opened door, approach the treasure chest and the level ends.