Bishui Cave — hidden place in Black Myth Wukong on Fire Breathing Mountain. You can unlock access to the cave after completing the quest with the bull named White Axe Fighter. You can find him and start the quest almost at the very beginning of the fifth chapter.
How to start the quest with the bull, find all the carts and unlock the Bishui Cave, you can find out from this guide.
How to get to the Bishui Cave
Find the White Axe Fighter
Find the teleport Ash Pass I, in the Smoldering Forest location and, after activating it, follow to the right. Run through the passage between the rocks, then turn left and follow the sounds of the struggle.
In the distance, you will find a bull fighting with yaoguai. Soon, you will have to engage in battle with him too. Once the battle is over, talk to the Fighter in white clothes. To start the quest, you need to listen to absolutely his entire conversation until he starts repeating the same thing.
The fighter will tell you about the carts of the five elements that blocked the way to the top of the mountain and will offer to destroy them.
First cart (brown with iron)
From the place where you fought the Fighter, go up the stairs until you see the first cart blocking your further path.
The second cart (gray with bronze)
The next cart can be found by following the path from the boss battle Father of Stones, reachable from Smoldering Heights.
After the fight with the Stone Golem, go through the gate and follow the stone path down into the cave. Follow the corridors lit by lights until you come across the exit of the cave at the end. Turn left and in a narrow passage you will encounter another Cart of the Five Elements.
The Third Cart (Scarlet and Silver)
Follow the Fire-Breathing Mountain until you reach the location of Hot Valley. From the rest point Emerald Hall go forward and fight the Guardian of the Fire-Breathing Mountain. Only after the battle with this enemy will you be able to gain access to the rest of the wagons.
From the arena with the throne of the Bull-Headed Prince's wife, follow the stairs up and run forward. Soon, another wagon will be on your way.
The Fourth Cart
Return back to the altar of Entrance to the Valley in the Hot Valley location and find the fourth cart, also connected with the quest Ma Tianba.
You can learn how to find the fourth cart, as well as complete the Guai horse quest and get a new spell, from a separate guide.
This time you don’t need to fight the cart, just interact with it and pull out the horse’s whip.
Talk to the Fighter with the White Axe
After destroying the first three carts and finding the fourth, return to the place of the first meeting with the bull to the teleport Ash Pass I. Talk to the bull and listen to his entire monologue again. After the Fighter gets stuck on the same phrase, move to the next location to listen to him again.
Teleport to the save Emerald Hall and run to the battle site with the cart (scarlet with silver). There you will meet the Fighter with a white axe again. Follow the same algorithm and listen to all his lines.
Fifth Cart (Red with Gold)
To get to the final cart of the five elements, you need to go through a rather long and confusing path.
First, get to the point Crater of the fallen furnace in the location Fire field. Turn your back to the save point and follow the left side along the return road from where you came.
Follow the steps as shown in the screenshots below, focusing on the towers sticking out of the ground.
Find the passage on the left that will lead you to the Flint Guardian boss field. Follow this area further until you reach a straight path that will lead you to the Cool Slope incense.
From this point, in the distance you can see a gate covered in snow. Go there, where a fight with the last fifth cart awaits you.
If you have not exhausted all the dialogues with the Fighter, the cart will not appear in the right place.
Defeat it and talk to the dying bull. After a short cutscene, you will finally have the opportunity to enter the secret area – Bishui Cave.