Exploring the three great Obelisks in the desert is a requirement for the achievement “King Deshret’s Great Sea of Scarlet Sands” in Genshin Impact.
Obelisks can be seen in many areas of the desert in Genshin Impact 3.1. Some of them are small while others take the form of large buildings. On the map, players may have noticed these large Obelisks, but upon visiting them, people will find that there is no way to enter.
This is because the entrance is hidden underground. Opening the doors to all three great Obelisks will grant the Achievement “King Deshret’s Great Sea of Scarlet Sands”.
Genshin Impact – “King Deshret’s Great Sea of Scarlet Sands” Achievement Guide

Location of the First Obelisk
After obtaining the secret base password from Thutmose in Genshin Impact, enter the hideout and make your way through the corridors until players reach the entrance to the large Obelisk.
Each Obelisk comes with a time challenge where players must collect some Dendro Particles. Complete the challenge to earn a Precious Chest and access to an elevator that will take you to the main floor of the great Obelisk.
Once you reach the main floor, investigate a release mechanism to open the door and bring an oasis into the surrounding area. No specific release level is required to accomplish this task.
Location of the Second Obelisk
For the second large Obelisk, go to the Teleport where players escape the Abdju Pit with Jeht and Jebrael. Follow the route to the Obelisk and finish the time challenge to get another Precious Chest.
As before, riding the elevator and investigating the mechanism will bring the area back to life.
Location of the Third Obelisk
For the final Obelisk, enter the underground Teleport area on the far left side of the Sumeru desert. Walk through the passage under the large statue and players will notice that this area is occupied by two fans.
There is a Forged Primal Light (white circle) that players must bring for their Replicator Keystones. The combination of the two will form a Primal Ember. Release Primal Ember as soon as the fan stops. If the Ember is hit by the wind current, it will dissipate and return to its last location.
Once Primal Ember returns to its Primal Torch, the fan that creates an updraft will activate. Players can now reach the top of the ruins. Those who own Zhongli and Venti can also skip these steps entirely, but will lose a Common Chest.
In later rooms, players will need an Anemo unit to reveal a Forged Primal Lights underneath a pile of sand, but the rest of the journey is pretty straightforward.
Once you reach the great Obelisk, investigating the third mechanism will grant the Scarlet Kingdom Red Sand Great Achievement.