I was making a water slide when I fell of while in a boat, strangely enough, it didn't break, but when I stepped out of the boat it did break.

I expected that the boat would break immediately when it touched the ground, but what happened was that it broke when I got out of the boat after it had fallen.

Also, in survival the player does not take any fall-damage because the boat does not break.

steps to recreate:
1. get a boat at high distance (on land or in water, it doesn't matter) (a distance that would normally damage an entity)
2. go inside off the boat
3. drive the boat off the cliff (it doesn't break)
4. step out off the boat (it breaks)