Falling into shallow water from height will not result in fall damage. This is different than pre-0.12.

To replicate in survival mode:

• Create a 2x2 hole at least 20 blocks deep.
• Place water at the bottom 1 layer deep
• Fall into this hole
• See that you receive no fall damage

What should happen – you should receive significant fall damage even though there is water at the bottom.

As asked and answered on reddit