I have a very deep vertical mine shaft (I started in a mountain and hit bedrock), so it takes a long time to get up or down using my ladder. To speed up the trip down I thought “why don’t I add a little pool for me to jump in?”, but when testing it out the first time I died and had to rush back to my mine to collect my items before they disappeared.
How deep do I have to make the pool in order to prevent myself from taking damage when I hit the water?
As of version 1.4.3, only a single block is enough to prevent all fall damage.
For previous versions it was 3 blocks.