How do you get Hidden in the Depths in Minecraft?

Ancient debris only generates in the Nether, most commonly around Y=15. Bring a diamond pickaxe or better - nothing weaker will drop it.

What kind of advancement is Hidden in the Depths?

Hidden in the Depths is a Nether tab advancement in Java Edition.

Hidden in the Depths

Tab: NetherDifficulty: Hard

Quick answer: Obtain Ancient Debris

Tree path: Nether › Hidden in the Depths (advancements are independent: they can be completed in any order; the tree only guides progression)

Tree parent: Nether

Advancements are exclusive to Java Edition. The Bedrock Edition equivalent is achievements, which have different objectives.

How to get Hidden in the Depths

Ancient debris only generates in the Nether, most commonly around Y=15. Bring a diamond pickaxe or better - nothing weaker will drop it.
Dig a main tunnel at Y=15 in any Nether biome (warped forest is the safest) and branch mine every 2 blocks.
Faster method: beds. Ancient debris is blast resistant, beds are not. Place a bed 4 blocks away, stand behind a block, click it to explode, and repeat down the tunnel. TNT works the same way.
Expect roughly 1-2 debris per chunk. For a full netherite set (36 ingots with the smithing template upgrades) you need 36 debris plus the template from bastions.
Smelt each debris into netherite scrap; 4 scrap + 4 gold ingots make one netherite ingot.

Tips

Beds explode in the Nether - always place a solid block between you and the bed before clicking, and carry a fire resistance potion. Ancient debris never generates exposed to air, so ignore open cave walls and mine solid netherrack instead.

Advancements this unlocks

Cover Me in Debris (100XP XP)

More guides from this tab (Nether): Nether Return to Sender Those Were the Days Subspace Bubble A Terrible Fortress Who is Cutting Onions?