Credits: StarkTMA
Main features:
- Kelp - is basically an underwater plant, which is needed in the oceans to produce oxygen for fish. 
 - Dolphin - a new type of mobs, can be spawned underwater manually, using spawn egg.
 - Fish - you can spawn them and kill to gain cool loot, use a fishing rod to catch them for loot.
 - The Monster of the Ocean Depths - a giant and ugly squid basically.
 - The Great Hunger - hostile mob.
 - The Hovering Inferno - mob that won't be added into 1.4 due to loose in Minecon vote contest.
 - The Monster of the Night Skies - the mob that won a Minecon vote contest.
 



How to install addons:
- Download addon into your device
 - Find and open .mcpack or .mcworld files that you download earlier
 - Click on it to import into Minecraft Pocket Edition
 - Open the game
 - Create new or edit an existing world
 - Scroll down to Add-ons section and select the ones you want to apply
 
Edited: 12.08.18
Reason: Turtles added.