The major adventure-related addition to Minecraft 1.8 will be Ocean Monuments.

These large underwater structures are guarded by new hostile mobs: the Guardians.

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And to get to the treasure at hidden in each Monument, you’ll have to defeat the Elder Guardians.

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These are tough enemies to beat and you will need good armour and ideally some good potions and enchantments to survive the challenge.

Prismarine

Ocean Monuments are built from a new kind of stone called Prismarine, and lit by Sea Lanterns. More new blocks for us to build with!