Calculation of the pressure under the water

Filling a 3-meter water pipe with water, and put it on the sea surface. According to the diameter of the water pipe, which is 15 cm, we can calculate the mass and height of the water column in the water pipe when the bottom of the water pipe is connected to the sea level.

 

Unfortunately, I didn't become a villain. The sudden increase in pressure in the pipe will only affect a small area under the pipe. At least I became a nightmare of those 7.07 square millimeters of stones under my feet.