East Biron Snowshelf Cave is north of Rospro Pass Skyview Tower and south of Eutoum Shrine.
Cave Location
The cave's east entrance is located at -3554, 3088, 0274, which is north of Rospro Pass Skyview Tower and south of Eutoum Shrine. The cave's western entrance is located at -3986, 3063, 0140, which is northwest of the skyview tower and southwest of the shrine.
Cave Features
From the east entrance, go down the slope to find a wall of boulders. Break them and continue going down the slope. You will find a campfire. Go toward it, but before you go to it, turn around and you will find another tunnel to the east, beneath the one that you came from. Hit the icicles to get them out of your way, and go to the end of the tunnel to find this cave's Bubbulfrog and some ore deposits, including a rare ore deposit.
Go west again to reach the campfire, where you will find Selmie. If you didn't already talk to Russ at Selmie's Spot, you can talk to Selmie to start the quest The Duchess who Disappeared.
Go west from Selmie and break down the wall of boulders. After that, talk to Selmie and she will return to Selmie's Spot, which will be marked on your map if you have "The Duchess Who Disappeared" quest active.
There are no more obstacles in the western tunnel beyond the boulders that you broke down, so you can shield surf west through the tunnel if you wish. There are various ore deposits and brightbloom seeds along the way.