Abandoned Mines - Dark Tunnels with Spike Pits

After climbing the wall of ice, follow the dark passageway down a short flight of stairs.

Turn left to find some mushrooms and a relic (1/1), A Father's Sword from The Athanatoi set (Greek).

NOTE: If you're not familiar with the Athanatoi, this Wikipedia article should prove enlightening.

Turn around and continue past the stairs you just came down, to the edge of a large spike pit. Jump across the stone pillars...

...to the L-shaped ledge on the right.

Gather more mushrooms and pass by the rope-wrapped barrier for now.

Dig up a coin cache (2/3) buried near the corner of the L-shaped ledge. Grab the arrows. (They're leaning against the far wall, hidden by Lara's arm in the screenshot above.)

Then carefully jump over the concealed spike pit.

In the alcove ahead is a pile of coins and an Explorer Satchel (1/1), which reveals the locations of any survival caches and strongboxes you have not yet found.

Turn around, jump back across the spike pit—do not attempt to walk along either edge of the pit or Lara will fall in—and return to the left.

Use a rope arrow to pull down the barrier in the arched doorway and go through.

Just ahead on the left side of the passageway is a ledge.

Climb up to find herbs, salvage, and a document (5/5), Broken Tracks from the Soviet Power series (Russian).

Drop down and continue to the left (northeast) toward the red light. Jump over another concealed spike pit and get some cloth from a container in a dead-end alcove.

Turn around and jump to latch onto the wall of ice above and to the left of the spike pit. Climb up to emerge in the RUINED CHANCEL WITH THE SHALLOW POOLS where you fought the first Trinity squad earlier.