This addon contains a biome pack that generates a world of shallow seas and marshlands.  I made this one by accident and found that many of the ships were raised to the surface.  Most of the vanilla biomes are represented but flattened a bit or changed in strange ways.

1.  Download the .mcpack file and run it on your device. This will start Minecraft and import the addon files.  

2.  Add the new behavior pack to your world.  

3.  Enable [Use Experimental Gameplay] in the world settings. This will be necessary until a future Bedrock update.  

4.  Finally, start your game.

Downloads

• ShallowSeas.mcpack

Supported Minecraft versions

1.12