While The Legend of Zelda: Breath of the Wild has many unique and entertaining mechanics, one gameplay element the game does not exhibit is underwater swimming. Link may tread above water and swim relatively short distances, but diving is unavailable to players yearning to explore the deep ocean. However, that doesn't mean Nintendo didn't provide detail for the sea floor, as indicated by one Twitter user who presented such detail in a video posted to Twitter.
Twitter user @eu_rasi_a_3678, who regularly posts gameplay videos and moments of Breath of the Wild, posted a video of an examination of the sea floor which shows a fairly detailed look at its design. As seen in the video below, the user swims underneath a low dock, his head colliding against it. With a manipulation of the swimming mechanics, the user traverses to a point in the water where, in first-person under the dock, the user can see underwater.
First using Link's binoculars, which implies that the player is being registered as above water, the user takes a view of the sea floor's flora, as well as the fish inhabiting the lake. They then swim further under the dock, more closely looking at all that the sea contains. Translated, the user's tweet says, "The sea of The Water Village," and, underneath, reads, "Fish flying in the coral forest."
Although disappointing that The Legend of Zelda: Breath of the Wild didn't allow for underwater swimming, it is fairly impressive that Nintendo developed an elaborate sea floor regardless. Furthermore, the aquatic plants and fish don't appear bland, suggesting that Nintendo took its time to really develop a living, breathing world, as was evidenced by the rest of Hyrule and its vibrant rendering.
Perhaps the underwater exploration, and water traversal altogether, is one of the things Nintendo will improve on in Breath of the Wild 2. However, there are other areas where Nintendo may concentrate its focus as well, such as weapon deterioration and other frustrating elements. Since the sequel's developers are playing Red Dead Redemption 2, it is quite reasonable to expect new and more advanced elements. Although, given John Marston's inability to swim, perhaps Red Dead Redemption 2 isn't the best for setting that example.