Entering the depths of the sea, Jason quickly realised that he was unable to see everything with his naked eyes.
Thus, he instantly activated his Emperor Eyes to see everything properly.
The darkness that slowly permeated the surroundings the deeper he got, prevented him from being able to see any other colors except occasional bright lights that flashed past him.
Having enveloped his entire body with a membrane of mana, while circulating some of it through his body, Jason gauged that he would be able to stay underwater for far longer than 20 minutes.
This should be more than enough to reach the bottom of the sea in addition to being able to find his way towards the mana vein.
Unfortunately, he forgot to consider one important factor in his calculations- attacks of marine beasts!