The first thing that you have to do is go to the statue of the seven on the west side of Sumeru city you will see that the city has gone underwater.
But now with so much care, you have to fly down if you lose control you can fall into the waterfall and you will find an area on your right side while you are flying down.
Once you will reach the area you will find Seelie on the top of the mechanic and you will also two sentinels there whom you have to defeat in order to open the seal on the mechanism.
How To Unlock The Underwater Teleport Waypoint In Sumeru
Once you defeat the enemies you have to then interact with the mechanism that will then lower the level of water and once the water level gets down you can either follow Seelie until you reaches the destination or you can take the left cave that will also take you to the same place.
And once you reach the place you will different Dendro Monuments there and now you have to use the dendro element at the rock covered by the vines to reveal the Dendrograna Tree and then summon Dendrograna and change to bow character as you will have to perform range attack.
Now you have to solve the Dendro Monument Wall Symbol Puzzle, and for that perform the charge attack to the rock emblem to reveal the elemental monument and after elemental monument revealed shoot again to activate the monument.
Now again summon the Dendrograna and head towards the east and climb to rocks and cross the red charged mechanism and after that you will find the second elemental monument and you have to activate that by performing charged attack.
And from there turn around and you will see rock with the green emblem shoot the rock to reveal the third elemental monument and activate that in the same way and if you ran out of dendrograna you can just go back to dendrograna tree and summon dendrograna.
Now you have to turn around head towards the southeast and go to the left side corner of green barrier then climb and move to the right to go through the gap.
And then use dendro element to activate the last elemental monument to break the seal on the mechanism. Then go to the mechanism and activate it to lower the water level and now wait until water receds and then go down.
There you will find enemies whom you have to defeat in order to activate the mechanism, now go to the mechanism and activate it to open the door then go through the door and climb the wall in front of you, keep moving and then climb the wall on your left.
Now you have to head toward the east now take the left side walk and the go straight, now carefully glide down and you will see domain on your left side, now summon dendrograna and then turn around and perform charge attack to the flying dendro objects.
And then interact the domain to activate it, go to statue of the seven on the west side of Sumeru city now head towards the west and go back to waterfall area and there you will see the waypoint on the below and you are done now.