You just need more numbers/sources. Intuition is a limited tool, especially in physics. According to this ( http://www.calctool.org/CALC/other/games/depth_pres

You just need more numbers/sources. Intuition is a limited tool, especially in physics. According to this ( http://www.calctool.org/CALC/other/games/depth_press http://www.calctool.org/CALC/other/games/depth_press ) the pressure would be around 15 MPa (this isn't hard to calculate by hand either). Consider that the mud/oil pushes 15 MPa, and water the same: that gives 30 MPa of purely compressive stress. Concrete could take this much ( http://www.cement.org/basics/concretebasics_faqs.asp http://www.cement.org/basics/concretebasics_faqs.asp ), and steel even more easily ( http://en.wikipedia.org/wiki/Tensile_strength http://en.wikipedia.org/wiki/Tensile_strength -- if I'm not mistaken, steel behaves roughly the same in compression and in tension).