As a person goes deeper, his eardrums will rupture before his organs could feel the pressure. Yi Yun blew up the air in his mouth. By increasing the pressure from his mouth, he could balance the external pressure surge, reducing the pain in his eardrums.
After diving to an unknown depth, Yi Yun experienced poor light conditions underwater. Only by looking towards the water surface would he see the beautiful sunshine being transmitted down.
In order to have a means of escaping danger, Yi Yun kept close to the cliff. Peppering the cliff were weird rocks. The rocks led downwards into a deeper depth that was complete darkness. It was a terrifying and bottomless darkness.
Thankfully, Yi Yun had reached the Vigor realm; his breaths could last him a long while. With one breath, he was able to endure about fifteen minutes.