Aground

This achievement is earned on the planet The Depths.

The first thing to do is talk to the NPC so he can offer you the quests you need to complete. He will then ask you to activate the 5 monoliths on this planet. There's one on land, one in the water maze, one in the deep ocean near the right wall, and two in the shallow ocean (if it's hard to find them, you can use the sonar that unlocks after completing the NPC quests).

Monoliths are activated by one bone shard, which is obtained by killing Lampfish and Sea Serpents in the depths of the ocean. To kill them you will need the following:

Torpedo Launcher: 2 Steel Bars, 2 Gold Bars, 2 Silicon
Torpedo: 3 Sulfur, 1 Steel Bar, 1 Silicon

Unlocked after finishing the "Unfathomable" quest:

Submersible: 5 Hi-Tech Parts, 8 Moissanite, 8 Diamonds, 1 Power Core
Mega Torpedo: 1 Gold Bar, 1 Crystal Frond, 1 Uranium
(optional) Sonar: 1 Hi-Tech Parts, 1 Moissanite, 8 Crystal Fronds.

Sea serpents can be killed in shallow water without the submersible, but this technique will be much more difficult. I personally kill lampfish and use mega torpedo, if you want to use this technique I recommend taking a water chainsaw (or any tool to cut trees underwater) that will be necessary to get crystal fronds that are obtained from trees that are in the ocean.

Once the 5 monoliths are activated, talk to the NPC to make The Dishonored One appear. To kill him, you must wait for him to attack you with the flood, which is when he has no shield.

Kill him and the achievement will appear.


(Sorry for my english, use the translator).