Java Edition 18w19a

18w19a is the thirty-third snapshot released for 1.13.

Gameplay

 * New effect: Dolphin's Grace.
 * Acquired by swimming near dolphins.
 * Makes the player swim faster.

Fluids

 * Separated some of the logic for blocks and fluids.
 * Current fluids:
 * The fluid at a location is currently dependent on the block at the location; currently there still are water and lava blocks.
 * Added two new fluid tags:  and.
 * This system is mostly internal; it cannot be directly interacted with yet
 * The fluid at a location is currently dependent on the block at the location; currently there still are water and lava blocks.
 * Added two new fluid tags:  and.
 * This system is mostly internal; it cannot be directly interacted with yet
 * Added two new fluid tags:  and.
 * This system is mostly internal; it cannot be directly interacted with yet

General

 * New Buffet generation type: Caves.
 * Creates Nether generation.

Blocks

 * Changed names and IDs of several blocks:

Items

 * Changed turtle egg inventory item texture.
 * Phantom spawn eggs now look more like the mob's updated texture.
 * Heart of the sea now generate in buried treasure chests (as stacks of 1).
 * Changed names of several items:

Mobs

 * All undead mobs (except for zombie horses) now sink.
 * It is uncertain if the Wither boss can sink because it cannot be seen sinking due to the fact that it will instantly start "flying" or go up once summoned.
 * Husks will morph into zombies after a while if they are in water.
 * Skeleton horses are now rideable underwater.
 * Phantoms now flap their wings smoother and faster.
 * However, in some games, phantoms do not flap their wings at all regardless of the game being updated to 18w19a
 * Phantoms will now drop experience.
 * Parrots will now imitate phantoms and drowned.
 * If dolphins start drowning, they will now swim to the surface.
 * Polar bears can now spawn on top of ice.
 * Changed the name and ID of pufferfish (mob):

World generation

 * Due to changes in world generation, worlds from previous snapshots will no longer work.
 * Seagrass now generates in underwater caves.

Command format

 * The output of the command can now be copied.

General

 * Improved the upgrade paths from old versions.
 * Updated the credits list.
 * Experience orbs will now float up in water.
 * The 'How Did We Get Here?' advancement now includes the Conduit Power status effect.
 * New sounds for conduit and beacon.
 * The F3 menu now shows the biome ID, rather than name.
 * Changed the names of several biomes:

Video
Video made by slicedlime:

Trivia

 * Unlike most of the first-of-the-week snapshots, this was released on a Tuesday instead of Wednesday.