Why can some insects walk on water?

The tension of the water surface and the small weight of insects allow them to travel on water without sinking.

The force of the insect's leg acts on the layer of 'tension' lower than the surface tension.

Water has a special characteristic. What is that?

Each water molecule is subjected to impacts from surrounding water molecules in all directions (molecular attraction) except for molecules located on the surface. Since no water molecule is located outside they are stronger inward force, which creates a surface tension that turns every water surface into an invisible 'tension film'.

In the meantime, some insects, such as paws or rafts, are very small in weight. Therefore, the force of the insect's foot acts on the 'tension film' layer lower than the surface tension.

Besides, insects always open their legs when walking on water so their weight is broken down and dispersed to each leg. As a result, their feet do not sink into the water but only create a "subsidence" on the surface that allows insects to move on the water.