This sequence is also shown in a short video walkthrough.

Now head to the back right corner.

Jump up the small slope and pull up into the doorway.

Turn left and follow the dark passageway.

There's another guard lurking at the far end. As soon as he sees Lara, alarms start blaring, but don't worry you can still get the secret. Kill the guard or just run past him.

Then jump from the left side of the opening, across a water-filled channel, onto the metal ledge below.

The frogman will have jumped down into the water and begun shooting harpoons at Lara. Kill him before he does too much damage.

Kill the first guard, who'll be firing at you from the open area ahead. Then jump into the water where you killed the frogman to claim SECRET #6.

In all you'll find 4 bunches of harpoons, a large medi pack, a save/power-up crystal, and a second UPV.

Pick up ALL the items and drive the UPV out of the secret room before saving again. If you save and reload, the invisible wall may prevent you from getting back into the secret room. If you already did this and the UPV is stuck inside, don't worry; there's another one coming up.

[Part 2 |Return to the Lud's Gate Walkthrough]