Duck Diving is an essential part of being a competent surfer. Duck diving is the way that a surfer dives under an oncoming wave as he or she paddles out to the lineup. Ducking under the wave ensures that all the progress made by paddling out is not lost by being washed backwards by the wave. The bigger the waves or the more frequent the waves are, the more important it becomes to be skilled at duck diving. This is something you are really going to have to get wired in your brain if you want to surf in crowds.