Find Another Way through the Cave – The Lord of Undvik – The Witcher 3 Wild Hunt
Follow the cave and jump down into the water. Defeat the two Erynias using your crossbow. Go back towards where you jumped down to the glowing part of the cave and climb up the ledges. Follow the blood trail until you get to a ladder. Climb up all the way to the top, follow the cave and turn right at the intersection.