Hydromancy
Hydromancy (Ancient Greek ὑδρομαντεία, water-divination, from ὕδωρ, water, and μαντεία, divination) is a method of divination by means of water, including the color, ebb and flow, or ripples produced by pebbles dropped in a pool. It also refers to the entering of a trance by staring at a chosen form of water, which is a form of scrying.