Minecraft 1.13 Snapshot 18w11a will have a new hostile mob. The Drowned has been added. The Drowned mob is like an underwater zombie. Shipwrecks, shripwreck loot and coral fans have been added this snapshot update too.
How to install:
Minecraft 1.13 Snapshot 18w11a Download Links:
Client: Download from Server 1 (.json)
Server: Download from Server 1