Minecraft Tutorial #7: Whirlpool in the ocean
Channel: RedMcNed
Date: 2015-04-15

Whirlpools, the stuff of myth and legend.  Minecraft, also the stuff of myth and legend.  Here's my take on how to build one.  Features include scariness, downward pulling water, and if you sail at an angle into it and let go of any controls you can ride it!  A word of warning though, this is a big project, but the principles apply if you want to make a smaller version.  
Edit:     I would HIGHLY recommend trying to make this first in creative mode if anything seems confusing.  I would consider this fairly advanced water mechanic manipulation.

Also, this is a larger version I made more recently in survival: https://www.youtube.com/watch?v=0nTVdSPOijg

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2:30     The temporary funnel structure needed
3:54     A scaled down quick example of the steps involved
7:13     Finding a location
7:58     Placing the first blocks
9:34     Building the cylinder
11:22   Draining the water (sponge-tastic)

12:55   IMPORTANT!!!   Preparing the sea floor to hold the water in place

16:10   Building the funnel
22:24   Placing the first water blocks
23:56   Removing the Funnel blocks
27:03   Placing the last blocks of water
27:21   Removing the cylinder
30:46   The finished product
32:12   Foreshadowing?

Feel free and encouraged to build this in your own world!

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