I noticed something interesting in nature yesterday. I was cleaning a sink that was full to the brim with water and once i was done cleaning my vegetables i pulled the plugged which (of course like we have all witnessed) created a vortex between the top of the waters surface and the drain. Which i figure is the same thing that happens in the ocean, yet i may be wrong about that, it seems like the same effect in principle at the very least. I put my finger on the drain which stopped the vortex and wondered how incredible nature is that it can suck ships with this same force and yet i can stop my finger with it. Of course on a much smaller scale. Anyways it got me thinking how would one calculate the force of a vortex like this. One being the simple drain vortex and another being a huge vortex you would see after an earthquake. Is it the amount of water or the size of the hole that makes the force increase or is their other variables i'm missing? Id love a layman explanation to this because i am not a physicist and then id love a technical explanation to this. As well as math equation if possible so that i could calculate the vortex forces myself. Thank you!