Mounts of Mayhem structures

I'm in awe of the new update and I absolutely love the nautilus. One thing I love about minecraft is the adventures I'd have with my world which is why I believe there should be more structures underwater. Especially since we're getting the nautilus, this would be a perfect opportunity to improve the oceans and get players to spend more time in the sea! I'd love it if the ocean was deeper (like increasing the built limit from -60 to -100 for example). If the ocean was deeper it would also be cool if the ocean got darker as well, therefore more use for more light blocks or light sources. More wood based varients. A lot of players (including myself) usually skip the coral reefs or go down just to take the sea lanterns. This is why I'd love if there were more coral blocks that could be crafted into wood tools and blocks. For example, a vibrant pink and/or red, or a light pastille blue and/or a mint green. An underwater civilisation. An underwater village would be crazy!! Similar to that of Atlantis, this could be hidden in the depths of the ocean populated by drowned or even new mobs like mermaids for example. Finally, even though there are over 1000 varients of fish, I would still love to sea more underwater animals and mobs. In my opinion, the ocean can be barren at times, which is why more animals would make the sea feel more vibrant and lively. Rarer animals like the pink dolphin or a blobfish would be amazing. I just want to sea a whale in minecraft in my opinion!!