Bow Riding is when dolphins surf in the wave created by boats and ships. As boats move along the water they create a wave. The dolphins are propelled forward by the wave and they will often twist and turn and even swim upside down as they glide through the water.
Wake Riding is very similar, it is when dolphins swim along and surf in the waves created by the back of boats and ships.
Dolphins will often leap in the air when bow riding or wake riding. We used to regularly see Billie surfing and even tail walking in both the bow waves and the wake that the boats created. We are still lucky to frequently see Wave and a couple of the other Port River dolphins Tail walking in the bow waves of the ships and tugs as they move up and down the river. It certainly is a great sight to see.
It is not known why dolphins bow ride. At times they may appear to bow ride to get from one area to another; however I have often seen them travelling in one direction and then they will race over to and ride the bow wave of a boat going in the opposite direction.
I therefore believe that bow riding is something dolphins enjoy doing and often do for fun, just like when people go body surfing.