Randomness. even if you knew down to meter scales what the currents were doing, it s still there s still enough randomness to shove or to push you from one path to another path. and so you can end up in different places tens of miles apart even though you started from almost the same point and you knew everything. turbulence is just it creates, it creates all the problems. right. at least we can get a much, much tighter control on it if we know how much is how much the wind is at play. but then, that s all talking at the surface. if once you start thinking about sinking, that adds this whole other dimension to the problem. at least the good news is once you go deeper, the currents are much less in strength. it s a lot also a lot more unknown because we don t have a lot of data of what s going on ....