Defeat a Ravager.

Use a Grindstone to get experience from an enchanted item.

Befriend twenty stray Cats.

Eat nothing but Kelp for 3 days.

Visit all Ocean Biomes.

Discover a Shipwreck.

Receive a gift in the morning from a tamed Cat.

Use Riptide to give yourself a boost.

Activate a Conduit.

Use a Dried Kelp block as fuel in a furnace.

Using the Frost Walker boots, walk on at least 1 block on frozen water on a deep ocean.

Use the Totem of Undying to cheat death.

Levitate up 50 block from the attacks of a Shulker.