Bedrock Edition 1.4.0

1.4, known as Phase One of the Update Aquatic, is a major update to Bedrock Edition that was released on May 16, 2018. It added many new features focused primarily around ocean-related content, such as dolphins, shipwrecks, fish, tridents, buried treasure, drowned, and the experimental Plutonium Mode. Some features were also fully implemented that were added through experimental builds from the 1.2.x updates.

Initially set to be released as 1.3, the version name was later changed to skip this number due to internal version tagging issues.

General

 * Plutonium mode

Blocks

 * Stripped Wood
 * Slabs and stairs
 * New slabs and stairs for all types of prismarine-related blocks
 * Coral Blocks
 * Trapdoors, buttons and pressure plates
 * New variants based on separate types of wood.
 * Kelp
 * Dried Kelp Block
 * Blue Ice
 * Coral Fans
 * Version exclusive : Can be placed on top of other blocks.
 * Version exclusive : Dead coral fans
 * Generate and function much like regular coral fans
 * Sea Pickles
 * Version exclusive : Player does not collide with it

Items

 * Trident
 * Heart of the Sea
 * Experimental : Nautilus Shell
 * Fish Buckets
 * Version exclusive : Bucket of Pufferfish has an unique texture, showing a pufferfish with old texture is filled by a water bucket
 * Enchanted books
 * New books for enchantments used on tridents
 * Dried Kelp
 * Spawn eggs
 * New spawn eggs for Drowned (only in experimental gameplay), Dolphin and fish mobs

Mobs

 * Experimental : Drowned
 * Version exclusive : Drowned equipped with trident will use do melee attack if target is 3 block or less from them
 * Version exclusive : Drop Sponge as rare drop.
 * Fish
 * Version exclusive : Will sometimes drop bones when killed.
 * Cod
 * Salmon
 * Pufferfish
 * Inflicts to the player if they get too close to it.
 * Tropical fish
 * Dolphin

World generation

 * Buried treasure
 * Shipwrecks
 * Version exclusive : Stripped logs generate as part of them.
 * Underwater ruins
 * Icebergs
 * Coral reefs
 * Ocean ravines
 * Underwater caves

Gameplay

 * Enchantments
 * Channeling
 * Only has one level.
 * Used on tridents to summon a lightning bolt on impact with a mob during storms.
 * Requires the target mob to be directly under an open sky and in a biome where it is raining.
 * Impaling
 * Goes up to level V.
 * Used on tridents to deal more damage to sea creatures.
 * Loyalty
 * Goes up to level III.
 * Used on tridents to make it return when thrown.
 * Riptide
 * Goes up to level III.
 * Not compatible with Loyalty or Channeling
 * Used on tridents to launch the player when thrown while in water or rain. Riptide will not throw the trident, but instead launch you forwards
 * If the player is not in water and it is not raining, the player is no longer able to throw tridents enchanted with Riptide, but they still deal melee damage
 * Players display a spinning animation when dashing
 * Other
 * New swimming animation

General

 * Most of the new features are no longer under Experimental Gameplay

Blocks

 * Rails
 * Can now be placed underwater

Items

 * Boats
 * Changed the steering of Boats when using keyboard and mouse by pressing W to move forward and S to reverse

Mobs

 * All undead mobs
 * Will now sink in water and can walk on the bottom
 * Husks
 * If sunk in water, they can now transform into zombies and then into drowned
 * Zombies
 * If sunk in water, they can now transform into drowned
 * Skeleton horses
 * Can now be ridden underwater
 * Skeletons and strays
 * Will now switch from ranged to melee attacks while underwater and switch back when out of water

World generation

 * Ravines and caves
 * Can now generate underwater

Non-mob entities

 * Items and block drops now float in water
 * The Player can now swim through 1x1 holes

Fixes

 * - Water flows down beside glass
 * - Transparent blocks underwater, when viewed underwater, have flowing texture
 * - Placing snow against the edge of a block places it two blocks away
 * Fixed several of the top crashes that occurred during gameplay
 * Fixed a crash that occurred when playing Truffletop Town and dying while using Elytra and Fireworks
 * Pick Block will now work in Survival mode
 * Players can once again resurface after tapping "fly down" arrow while swimming with touch controls
 * Fixed Dolphins getting stuck in their idle animation
 * Firework Rockets now appear in the Recipe Book when being searched for in Survival
 * will now clear items properly
 * The first mouse click after re-mapping an action to a key is now recognized
 * Improved messaging when there are no Old Worlds to sync
 * Leads can no longer be attached to Horses being ridden by players
 * Enchantment names can now be seen on the Enchantment Table screen with Pocket UI when using keyboard and mouse
 * Fixed helmets being visible after being destroyed by taking damage from a mob
 * Resource and Behavior Packs are now properly enabled/disabled on Realms when restoring backups or replacing worlds
 * Changes made to the 'Trust Player Permissions' setting during world creation will now persist after loading into the world
 * Ladders no longer appear as invisible blocks with collision when placed using '/setblock'
 * The surface of water can now be seen when viewing from behind glass underwater
 * Sneaking and jumping into water no longer prevents jumping or swimming upwards
 * Double doors once again display correctly
 * Fixed the texture of Dark Prismarine Stairs
 * Banners are no longer consumed from the inventory when placed in Creative mode
 * Pick Block will now pick the proper variant of Buttons and Pressure Plates
 * Glass once again renders properly at further distances and certain angles
 * Zombie Villagers created during world generation are no longer super fast
 * It's once again possible to eat Raw Fish
 * It is no longer possible to refill breath by swimming against ice
 * Fixed a redundant gray line at the top of the Drowned's legs
 * The Trident will now be thrown the direction the cursor is pointing when playing in VR
 * Pressing the 'Default Settings' button will now only affect the control scheme that is selected
 * Personal Game Mode is now fully applied in Game Settings when switched from Survival to Creative
 * The Ender Dragon will no longer get stuck if the player moves too far away. Silly dragon!
 * Dropped items can once again pass under top slabs
 * Image thumbnails and game modes for worlds and world templates will now appear when searching on the Storage screen
 * The book on the Enchantment Table screen no longer overlaps the suggested enchantment's name
 * Tall birch trees will once again generate in Mutated Birch Forests
 * Mobs will no longer rotate their heads 360 degrees while in Boats
 * Fixed water not rendering when viewed at certain angles near the surface
 * A controller tooltip will now appear when it is possible to place blocks underwater
 * All overhangs and floating islands will once again generate with grass or snow under them
 * Bryce Mesa biomes will now generate correctly
 * Fixed entering a Minecart from another Minecart
 * Blocks can no longer be placed with no other block to support it when sprint-flying underwater in Creative mode

Video
Video made by slicedlime: