I'm doing an investigation on how the speed of a wave varies as the depth of water changes, using a tray of water. I know that in deeper water the speed will be quicker than that in shallow water. However I don't quite understand why this is. Apparently it has something to do with Stoke's Law? Is it related to the viscosity and the flow of water in different conditions - the more volume there is, the faster it will travel? Please help me with the theory behind it to help me understand better.