Surface Tension of Water
In this picture above it can be seen that the gecko is standing on the water, but how?
Well, in between the water molecules in this tank there are hydrogen bonds that connect the molecules together. What is surprising is that the gecko is able to stand and walk on the waters surface and not just stand on the surface. You can see that the water is 'bending' under the weight of the gecko and that the bonds in between the molecules have enough force to not break and let the gecko fall through.
The way the gecko is able to stand on the water is to maximize its surface area as to not put all of its downward force onto one spot on the water. This works on the same principle that a snow shoe works. The larger the surface area, the more weight can be held by the water. This also works if a leaf is thrown onto some water, the leaf does not float but rather does not even break the surface of the water.