^^. Im curious.

willie is right n it can be explained much emphatically with the help of archimedes principle n newtons law of gravitation.

Yup, Something like your legs (Wincing thinking about compound fractures)'cause if you dropped the something, it would be traveling at the same speed and wouldn't do anything, whereas (I believe) the inertia you used to throw an object would actually slow you down due to Newton's third Law: Fg = The force of gravity (typically in newtons)
G = The gravitational constant, which adds the proper level of proportionality to the equation. The value of G is 6.67259 x 10-11 N * m2 / kg2, although the value will change if other units are being used.
m1 & m1 = The masses of the two particles (typically in kilograms)
r = The straight-line distance between the two particles (typically in meters)
This equation gives us the magnitude of the force, which is an attractive force and therefore always directed toward the other particle. As per Newton's Third Law of Motion, this force is always equal and opposite. You Were definitely right about holding your nose, because you could equalize the pressure once in the water and save your eardrums.. When I was a younger fellow, BACK IN THE 70'S-lol We used to jump off the top of a train trestle into the River 60 feet below. luckily the water was about 25 feet deep. Kind of funny story 'cause once I jumped into the river swam to the bottom to check for loose change and found the keys to my brothers van that he had lot 2 YEARS previously.

Been playing GTA4? This can be done in that game and you live but in real life hitting the water at a fast speed will kill you:
look at it this way;
you are 3000 feet in the air traveling at say 130 mph in a plane so upon dropping you already have speed now I forget the increased rate of fall average as in for each mile your speed increases by. But I think it is about 3-4 fold over initial speed so lets say at point of impact you are traveling at 300+ mph now water is liquid but have you ever done a belly flop wrong and feel it sting? Upon impact it will be like hitting a wall, your bones will separate from their joints basically you will hit and it will be like a cookie press it will flatten you and expand your body [or try to] this will most likely cause a brain hemorrhage and will possibly flatten your chest cavity as in your ribs will shatter and could very well end up stabbing your heart if it didn't explode already, Now before all this happens you will have passed out due to the force of wind entering your lungs in which will cause a vacuum which will cause them to collapse, from this you will suffocate and eventually pass out.

What he said.

If by some miracle you survived the impact, the speed you resurfaced from the depths in your panic would probably kill you anyway.

well if i do this and suddenly don't appear on KAT you know i've hit the water like a ton of sh*t....

Definitely not... Although... as with everything in life.. you DO stand a SMALL possibility of surviving... (altitude... velocity upon impact... etc etc etc...)

No. The speed plus the density of the water would make it feel as if your body was hitting concrete. You die. Then again, what's the altitude?

It depends on how lucky you are. But most probably a person will die

no you pending ocean depth either be buried in the dirt when you hit or die on impact