Why can't the axe in the underwater shelter be opened?

1, find the NPC in the hippocampus and accept the mission "Underwater Shelter" is the mission branch of submarine Vaschel. Use the task items in the backpack or click on the big shell behind him, with a small red bead behind it.

2. Players need to use Erunak's divination ball to observe the location of the dense fog cave.

3. Unlocking failure means that the previous task has not been completed, which needs to be completed first, and then unlocked by the above method.