Yesterday's Minecon Earth show brought several Minecraft-related announcements, one of which is the Update Aquatic which brings underwater life to the game. Soon, Minecraft will feature dolphins, coral reefs, shipwrecks, and more.
The update splits the oceans into iomes, and each will have different types of fish, coral, and kelp. If you want to build an aquarium, you can catch fish with a bucket so you can place them elsewhere. The sea will hold secrets too, including treasure. These can be found in shipwrecks and around icebergs. Dolphins will swim towards treasure to guide you to the plunder.
The Update Aquatic also introduces a new weapon: the trident. It can be used for both melee and ranged attacks. You can throw it to spear an enemy, but doing so will have the item disappear. Enchanting the trident, however, has it return back to you after each use.
At Minecon Earth show, it was also announced that both the Super Duper Graphics update and multiplayer cross-play for Switch are delayed to 2018. As for the Update Aquatic, it comes to Minecraft as of spring 2018.