stamina does not recover when in a boat (possibly in other transport, but I have not checked)
I also want to point out, in addition to other people, the movement in the boat, in theory, should spend endurance, because you need to row with oars.

This was intentional due to some funkiness with detecting whether the player was in a vehicle or not. I will probably fix this in the next major update.

Will be fixed once 2.0 is released.