In front of Popla Foothills Skyview Tower, you find Popla Foothills North Well.
Well Location
This well can be found at 0597, -2102, 0093, at the base of the Popla Foothills Skyview Tower.
Explore the Well
After you fall into the well, you land in a pool of water. Go to solid ground and use Ultrahand to take the treasure chest out of the water. Open it to get a Claymore.
If you don't have a fused heavy weapon, you can use Fuse with the Claymore and one of the nearby boulders to make a boulder hammer, then you can break down the wall of boulders with it.
On the other side, talk to Elmerson, who is behind bars. He explains that he came in from a cave entrance to the south, so use Ascend now to leave the cave, and go south. The southern cave entrance is at 0608, -2213, 0052. This is Popla Foothills Excavation Site. Go north to the bars and step on the switch to free Elmerson, then you can use Ascend to get back to the Popla Foothills Skyview Tower.