Cor Kalom's apprentice 
Caine has gone missing, and he sends you to track him down. The trail starts with a clue in Caine's hut, leads through the Swamp Camp's people to 
Lester, and ends with a long, mostly underwater push through the Abandoned Mine to where Caine is hiding. Watch your breath, because a lot of this quest is spent below the surface.
Half of this quest is underwater, so come ready for the swim as much as the fights.
- Healing potions.
- Food.
- A decent weapon.
- A torch.
- A
pickaxe if you want to mine the ore in the mine. - As much underwater breath as you can manage.
You dive several times, some of it against a current, so do not start until your breath holds up.
Start with Cor Kalom in the Swamp Camp to open the quest. On your way out, a Templar stops you and gives a first hint about where to look for Caine.
Head down into the Swamp Camp toward Caine's hut. You will know the spot by the two people standing nearby. Talk to 
Nyras, who tells you Caine's hut is right here.
Go past the man smoking on the ground and over to the hut in the back-right. You can pick it out by the paintings on the floor and the piece of artwork at the back. Take the artwork, then head back to Nyras.
Speak to Nyras again and he reads something into the clue, pointing you at Lester next.
Lester is at the start of the Swamp Camp, just past the first guards. Talk to him to learn that the next lead is the Abandoned Mine.
Be straight with people through this quest. Keeping their trust matters for how it plays out.
Make for the Old Camp, cross the bridge nearby, and head right, back toward the stretch of land where the game first began. Follow the path up. It should look familiar from the opening, and the enemies along here are not much trouble.
Carry on to the bridge above and turn right toward the old mine entrance. The guard outside will not just wave you in. Tell him you are investigating, then that it is something for 
Raven, and he hands over the key and lets you pass.
Inside, the mine is worth exploring, and there is ore to mine if you brought a pickaxe. Push through until you reach a crouching section, duck through it, and follow the train line. Past a water section you meet a spider, so put it down, then go left into the large cavern with the huge underground lake.
Dive into the lake and look for the big blue glow at the bottom. Swim down, grab the mechanism, and surface for air in good time. Then swim to the very back of the lake and climb the tall ladder all the way up. At the top, go left and take a running jump across the gap so you do not drop back into the water.
Use the mechanism on the device up here to open the gate below. Drop back into the water and swim through the gate that just opened, keeping an eye on your breath the whole time.
Beyond the gate you reach a waterfall. Climb down the ladder or jump into the water, and mine here too if you like. Then dive, because there is a chest full of loot directly below you that is easy to swim straight past. Open it, take everything, and come back up for air.
Dive again and keep going, always swimming against the current. If you are fighting the flow, you are going the right way. Push through the flooded, caged sections, surfacing for air whenever you can, until you come up near another waterfall and reach dry land in the old mine connected to Caine.
There are enemies here, so heal up and save before you go on.
Further in, a larger enemy is waiting. If you have put the time in training with 
Diego you should be able to take it. Kill it, loot it for the useful gear it carries, then look into the distance to spot Caine. That is the lost apprentice found.
Head back to the Old Camp and tell Raven what happened. Then return to the Swamp Camp, give Cor Kalom the news, and the quest is done.