Another possibility was that Dong Tianyu had now entered the Mysterious Realm, which was why his Divine Sense couldn't leave the cabin.
After all, it was his own Companion Spiritual Treasure. No matter what, Dong Tianyu still had some understanding of it; hence the first possibility, although present, was not very likely.
Along with the prompts from the Mysterious Realm received in his mind, Dong Tianyu also confirmed that the collision that caused his body to wobble just now must have been the vibration produced by the collision between the Mysterious Ship and his Companion Spiritual Treasure.
What Dong Tianyu never expected was that at such a deep depth underwater, he could still collide with the Mysterious Ship.
However, Dong Tianyu hadn't projected his Divine Sense outward just now, so he didn't know what kind of Mysterious Realm it was.