Sleep with the Fishes

Stay underwater for one full day without using potions.

Castaway

Eat nothing but Kelp for 3 days.

Free Diver

Stay underwater for 2 minutes.

1 Pickle, 2 Pickle, Sea Pickle 4

Place four Sea Pickles in one block.

Moskstraumen

Activate a Conduit.

Alternative Fuel

Use a Dried Kelp block as fuel in a furnace.

Echolocation

Bribe a Dolphin.

Saddle Up

Tame a Horse.

Overpowered

Eat a Notch Apple.

Change of Sheets 

Dye your bed a different color.

You Need a Mint

Collect Dragon's Breath in a Glass Bottle.

The End... Again...

Respawn the Enderdragon.

Cheating Death

Use the Totem of Undying to cheat death.

The Deep End

Defeat an Elder Guardian.

Feeling Ill

Defeat an Evoker.

So I Got That Going For Me...

Lead a Caravan containing at least 5 Llamas.

Tie Dye Outfit

Dye all 4 unique pieces of Leather Armor.

Taste of Your Own Medicine

Poison a Witch with a Splash Potion.

Dry Spell

Dry a Sponge in a Furnace.

Camouflage

Kill a Mob while wearing the same type of Mob Head.

Let It Go! 

Walk across the surface of a deep ocean by freezing the water with Frost Walker boots. 

Adventuring Time

Discover 17 of the 40 different biomes.

Super Sonic

Use an Elytra to fly through a 1 by 1 gap while moving faster than 40 m/s.

Trampoline

Bounce 30 blocks upward off a Slime Block.

Beam Me Up

Teleport over 100 meters from a single throw of an Ender Pearl.

Great View From Up Here

Levitate up 50 blocks from the attacks of a Shulker.

The Beginning.

Kill the Wither.

The Beginning?

Spawn the Wither.

Super Fuel

Power a Furnace with Lava.

Beaconator

Create and fully power a Beacon.

Map Room

Place a fully explored Map into an Item Frame.

Mine!

Open every chest in a Battle mini game arena in one round.

'Tis but a scratch

Take 100 damage in a round of a public Battle mini game.

...has become the master

Win 3 public Battle games in a row.

Cupid

Kill 2 players in a round of a public Battle mini game using a bow and arrow.

Hunger Pain

Kill a player while you are starving in a Battle mini game.

The Student...

Win a public Battle mini game.

Back from the Dead

Win 3 rounds in a row after one of the opponents has won 2 rounds.

Hotshot

Hit a Player with a Snowball while falling into the Lava.

Snowplough

Push three Players into Lava using Snowballs.

Underdog

Win a Tumble game whilst on the lowest layer in a Snowball Tumble Mini Game.

S-No Throw

Win a single round of Snowball Tumble without throwing any Snowballs.

Snow Storm

Hit a single Player with 25 Snowballs in a single public round.

Overlord

Stay on the top layer while winning a round in a Snowball Tumble Mini Game.

The Haggler

Mine or purchase 30 Emeralds.

Pot Planter

Craft and place a Flower Pot.

Zombie Doctor

Cure a Zombie Villager.

Sniper Duel

Kill a Skeleton with an arrow from more than 50 meters.

When Pigs Fly

Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Overkill

Deal nine hearts of damage in a single hit.

Enchanter

Construct an Enchantment Table.

Into Fire

Relieve a Blaze of its rod.

Return to Sender

Destroy a Ghast with a fireball.

Lion Tamer

Tame an Ocelot.

Librarian

Build some bookshelves to improve your enchantment table.

Delicious Fish

Catch and cook a fish!

Passing the Time

Play for 100 days.

Leader Of The Pack

Befriend five wolves.

Dispense With This

Construct a Dispenser.

Repopulation

Breed two cows with wheat.

Archer

Kill a creeper with arrows.

MOAR Tools

Construct one type of each tool (one pickaxe, one spade, one axe and one hoe).

Renewable Energy

Smelt wood trunks using charcoal to make more charcoal.

On A Rail

Travel by minecart to a point at least 500m in a single direction from where you started.

Iron Belly

Stop starvation using Rotten Flesh

Have a Shearful Day

Use Shears to obtain wool from a sheep.

The End.

Kill the Enderdragon.

The End?

Enter an End Portal.

Diamonds to you!

Throw diamonds at another player.

DIAMONDS!

Acquire diamonds with your iron tools.

Body Guard

Create an Iron Golem.

Music to my Ears

Play a music disc in a Jukebox.

Stayin' Frosty

Swim in lava while having the Fire Resistance effect.

Local Brewery

Brew a potion.

Acquire Hardware

Smelt an iron ingot.

It's a Sign!

Craft and place a Sign.

Bake Bread

Turn wheat into bread.

Pork Chop

Cook and eat a pork chop.

Chestful of Cobblestone

Mine 1,728 Cobblestone and place it in a chest.

Hot Topic

Construct a furnace out of eight cobblestone blocks.

Getting an Upgrade

Construct a better pickaxe.

Time to Mine!

Use planks and sticks to make a pickaxe.

Monster Hunter

Attack and destroy a monster.

Cow Tipper

Harvest some leather.

Benchmarking

Craft a workbench with four blocks of wooden planks.

The Lie

Bake a cake using wheat, sugar, milk and eggs!

Time to Strike!

Use planks and sticks to make a sword.

Time to Farm!

Use planks and sticks to make a hoe.

Into The Nether

Construct a Nether Portal.

Rainbow Collection

Gather all 16 colors of wool.

Iron Man

Wear a full suit of Iron Armour.

Getting Wood

Punch a tree until the block of wood pops out.

Taking Inventory

Open your inventory.