Question

Why can't you walk on water?

Answer 1

Technically speaking, walking over pure water isn't possible. The only way it can be done is by converting it to a high density fluid or one with high viscosity. Also, if you think you can run at 108 km/hr (30 m/s), then you'll have the ability to run across water.

Answer 2

This happens because of surface tension. Water molecules are attracted to each other. They form weak bonds between each other. Where these molecules meet air, the exposed water molecules can't attach to any more molecules in front of them — there's air there.