What If All Living Things on Earth Lived in the Oceans?

"At present, just 15% of life on our planet resides in the oceans. But in this scenario, we're taking a dive! You and all life on Earth are making a move to live underwater. Would we need to adapt to make this work? Which creatures would excel in this new world, and which ones might face challenges? Let's dive into the underwater transformation!"
video credit@What If
https://www.youtube.com/watch?v=UOY_bxvRcVA