 Surface tension occurs purely due to cohesion, in case of water. The intermolecular forces of water forms a barrier, a surface, a layer that stops the object from penetrating through, if you completely submerge the object it will fall through the water. How exactly do intermolecular forces form this surface? Let's think about it, here's a bunch of water molecules, do you think the water molecules at the top or the bottom or middle have the most intermolecular forces acting upon them? But the answer is actually the ones at the top. This is because the molecules in the middle have more molecules to exert intermolecular forces upon, so these forces are weaker individually, should oxygen needs to share the electron density and the hydrogen needs to take the electron density from those oxygen of other molecules, but there is a threshold to how much the oxygen can share and of how much the hydrogens want to take. The water molecules at the top first have less water molecules to exert intermolecular forces upon, hence individually, those forces are stronger, forming a strong layer at the top. Now let's talk capillary action. Capillary action is a result of the balance between adhesion and cohesion, tipping off onto adhesion. So if cohesion is the attraction from two molybd molecules, then adhesion is the attraction from two unknown molecules. Since our topic is water, cohesion is when water sticks together, and adhesion is when water sticks on the other surfaces. Let's look at these two tubes partially submerged in liquid. If cohesion is much stronger than adhesion, the force holding liquid together is much stronger than the force created by the liquid sticking onto the tube. Then we will not see the water drawing up the tube at all, and it will form a convex meniscus at the surface due to surface tension, like a half bubble, a real life example for such liquid is mercury. Now if adhesion is stronger than cohesion, then the water will draw up the tube, because the system is much more stable when the liquid sticks to the size of the tube via adhesion than to each other via cohesion. And of course, because cohesion is still there, the liquid moves along the tube, and creates more adhesion. All together, adhesion drawing the water up, and surface tension, all cohesion keeping the water down, creating a concave meniscus. Now let's say that we have three tubes of different widths, partially submerged in water. Which tube would have the water being drawn up the highest? It would be the narrowest tube. Why? Because the biggest tube, the more cohesion that is within the water, whereas the increased surface area didn't create more adhesion at the same rate.