Any body of water has the capability to produce waves, from a disturbance to standing waves. If you drop a pebble in the water then it will create a wave around it from the point where it dropped. This wave is caused by a force, and the more force something has, then the higher (amplitude) the wave will be. A standing wave can be seen when the water is "wavy" or "rough." The reason the waves don't just disappear after the hit the shore is because waves "bounce" off of the shore. After it bounces it changes direction. When two waves are going in the opposite directions but have the same [amplitude] then this causes a standing wave.