Find the New Prismarine Palace Scatterd Throughout the Oceans of your world and fight the new Boss the Prismarine Protector once you have killed the Prismarine Protector you will get the Key to The Under Ocean, light the dark prismarine portal frame in the boss room and explore the new dimension, you can also kill the Prismarine Golems in the new structure to craft prismarine armor out of prismarine bricks!
