Once you've obtained this chest, you can leave. Switch the map to Meigu Lake and teleport to "Ice Lake Dock."
If it's not unlocked, you can simply teleport to a nearby island and sail over. It's easy to spot in the white expanse. Just pass through this small hole.
Save your progress after landing. Walk forward a few steps to trigger a cutscene where Old Root appears. After watching the cutscene, you'll obtain the Shadow Armament "Dump Truck."
