Whether you survive a fall from a plane into water will depend on how far you fell from the plane into the water.
It certainly is not gonna feel good when you do hit the water from falling from a plane without a parachute and it's gonna hurt and possibly rupture some organs if you fall at around 135 MPH or faster into the water.
The higher up you are when you do fall into the water the less chance you have of surviving because if you fall fast enough into the water it can rupture organs and even break ribs etc which can lead to death.
If you are up in the air at 250 feet and fall into the water then you have a better chance of surviving the fall into the water but if you are higher up in the air than 250 feet then your chance of surviving the fall into the water is much less but still it's possible.