In the excitement phase, things are gettin' goin', blood is rushing to all the necessary places, genital areas are becoming engorged and secreting lubricant.
The challenge was immediately obvious-- water the color of cold coffee, almost no visibility, swimming against a torrent of water, the engorged stream that runs through the cave.
It's like this engorged beast that's been feeding on the options world that it is making the market more volatile in the middle of the day and could potentially cause a major stock market upset, let's say.