New Mobs:
-Glow Squid
-Axolot
-Goat
-Warden

New Items:
-Amethust Shard
-Brushes
-Bucket of Axolot
-Bucket of Powdered Snow
-Bundles
-Ceramic Shard
-Copper Ingot
-Spyglass

New Blocks:
-Block of Amethust
-Budding Amethust
-Amethust Clusters
-Azalea Leaves
-Azalea Bush
-Azalea Roots
-Calcite
-Candle
-Clay Pot
-Copper Block
-Copper Ore
-Cut Copper
-Cut Copper Slab
-Cut Copper Stairs
-Dripleaf Plant
-Dripstone Block
-Hanging Azalea Roots
-Pointed Dripstone
-Moss
-Powdered Snow
-Spore Blossom
-Dark Stone
-Sculk Block
-Sculk Trap
-Sculk Chute
-Sculk Sensor
-Sculk Growth
-Tinted Glass
-Tuff

New Biomes:
-Deep Dark
-Dripstone Caves
-Lush Caves

Cave Types:
-Mesh Caves

Structures:
-Excavation Sites
-Azalea Trees
-Geode


For more information
https://minecraft.fandom.com/wiki/1.17_-_Caves_and_Cliffs