
The main walkthrough includes general notes on achievements/trophies, navigating in the Extreme Depth Suit (EDS), and using chaff flares. The goal for the first achievement/trophy is to use all 10 chaff flares to divert torpedoes. Start by swimming down out of the hatch...

...and forward toward the gap in the rocks. Ahead is a rock outcropping that forces you to turn left or right. Go right.

Swim between the rocks to an open area with a hostile submersible. The sub will start shooting torpedoes at Lara.

Drop a chaff flare.

Then move away from it.

The next few torpedoes should zero in on the flare instead of Lara. If you turn to face the spot where you dropped the flare...

...you can watch this happening.
Spamming the flare button doesn't work because some of the flares will inevitably go out before they can attract a torpedo. So it helps to drop a flare, wait for it to go out, then drop another. If you're having a hard time seeing whether a dropped flare is spent, note that each flare lasts about 13 seconds. So if you drop a flare, swim out of the way, and count to 10-ish before dropping another flare, each flare should have time to attract a few torpedoes.

Repeat this sequence: Drop a flare...

...and count to 10 as you swim away from the flare (and the submersible).

As you count, watch to make sure the next few torpedoes target the flare. Then drop another.

Repeat until you've dropped all 10 chaff flares, and the achievement/trophy should unlock. Now, either reload if you want those flares back, or continue to the secret.

Try to avoid the submersible as you swim along the left side of the rusted U-boat hull. Locate the small opening in the rocks, below on the left.

Inside is a golden rose (1) (118/239) (SECRET #1, 16/36), the only secret in this level.

When you have the rose, turn around and swim out of the cave. Head upward and to the right.

Hurry past the mini-sub (drop a chaff flare if you still have any) and return around the rocks to the right, toward the big submarine where you began the level.

If you pause near the waving clump of seaweed at the top of the slope, you may be able to lure the little sub into firing a torpedo toward the big sub.

A direct hit on the big sub will unlock the "Silent Raider" achievement/trophy.
NOTE: If you don't get that achievement here, you can try again with the second small sub, as shown in the next section.
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