There’s nothing like floating in cold and refreshing water, on a hot day, as a way to relax. It’s the quickest way to inner peace, at least for me it is. Apparently, though, there’s a biological reason for it.
According to this Imgur thread, there’s a specific reason why, when you’re having a panic attack or feeling anxious, you should splash cold water on your face.
It’s all the spleen’s fault.