I'm stuck in the Lanayru mine. I've gotten to the northwest cave, across the large lake of quicksand. There's a locked door, and a mining cart I can't push anywhere. To my left is a quicksand-filled tunnel that seems to be the only place I can go:
I've tried running across. I've tried rolling across. I've gone back to the start of the mine and triggered the time crystal in the basin, hoping it would reach this portion of the cave. None of that worked.
Where do I go from here? Is there a way across this quicksand? Or do I need to go somewhere else?