You find Sawson at the Eldin Canyon Skyview Tower, and you learn that the door won't open.
Tower Location
Eldin Canyon Skyview Tower is located at 1638, 1182, 0225, which is east of Woodland Stable and Ekochiu Shrine.
How to Open the Tower
You find Sawson at the tower, saying that the door won't open. However, the lid at the top fell off, so you can climb the tower and fall into the top to get into the room on the other side of the door below. You may need to bring stamina food or upgrade your stamina meter by collecting Lights of Blessing from shrines and praying to a Goddess Statue, but there are flat places on the tower where you can stand and catch your breath.
After you make it to the top, fall down through the opening at the top to glide down to the room in the tower. Check on the terminal and the door will open.
Map the Region
After you reach the tower, open the door and examine the terminal to activate the teleport location here. Then step onto the glowing spot in the tower and examine it to be launched upward and map the Eldin Canyon area.