PIPeline
Pipeline (also known as either "Banzai Pipeline" or "Pipe" is located off of the North Shore of O'ahu and hosts surfing competitions every year, featuring only the most elite and skilled surfers. One of the major factors that enables Pipeline to produce such gargantuan waves is the coral reef below the surface. Like the rest of Hawaii's island reefs, these coral reefs grow on top of all the cooled lava. Furthermore, because O'ahu is one of the older islands, the reefs and lava are much smoother, when compared to the newer reef formations of the Big Island, because there has been more time for erosion to gradually smooth things out and make them less rugged. Furthermore, the bathymetric features caused by these smoothed out reefs are also important. Because of the reef, which rises up suddenly, the waves suddenly focus their energy on the shallow reef, creating a nicely shaped wave with a very surfable shoulder. Like many other places on the North Shore of O'ahu, Pipeline gets big around October through March because this is the time that many ideal conditions are met to produce the massive waves at Pipeline. Arctic swells dropping down produce strong North Pacific NW winds, which when mix during a big storm with warm, tropical air, causes a chain of effects that produce big waves at Pipeline. These mixing of airs causes lowered barometric pressure at the surface of the ocean, more wind at the surface in low-pressure regions, which then produce bigger swells and waves because of stronger winds, and west to east storm movement because of jet streams in the North Pacific. So when Pipeline gets a good NW swell, it goes off. Also, it is interesting to note that a lot of more Northern swells are actually blocked by Kauai (called the Kauai Shadow). Another factor that affects the waves at Pipeline is the amount of sand on the reef. Conditions are best later in the season when strong currents going back out to the ocean have swept much of the sand off the reefs. During the early season, before the sand has been swept off, the waves are of poor quality, with weird features throughout the wave that are very dangerous to anyone surfing the wave. Furthermore, because of the three different nearshore reefs at Pipeline and many offshore reefs, the swell period has to be specific in order for the waves at Pipeline to be good. If the swell periods are longer, then they are affected a lot by the outer reefs as opposed to shorter swell periods who are not as heavily affected by the outer reefs. The waves produced here are classic left waves (when the surfer drops down onto the wave, he/she will go left because that's where the face of the wave will be, with the portion of the wave to the surfer's left is breaking).