wave traveling twice as fast the group. In general waves will be referred to as either short period (15 seconds or less) or long period waves(16 or more seconds). The swell period will give you information about how the swell will affect specific breaks differently. These three pieces of information are the main key to forecasting the surf. If there is a swell of significant height that is headed in the direction of the break you are forecasting for, then there probably will be good surf. The swell period will tell you how much a swell will wrap into a spot and how much it will grow in deep water. Using bathymetry to predict surf for a specific break Wrapping and refraction One important fact about waves is that they focus more of their energy towards shallower water. Waves will always turn and refract towards shallower water. This is where swell period can drastically affect the conditions. The longer the period of the swell the more it tends to wrap into a spot. This means that a swell might cause waves in a spot even if it is not directed at the spot. Significant underwater irregularities, such as underwater canyons and sea mounts, can also affect how the waves come into a surf spot. Irregularities like these may cause the surf to be much larger at one spot, while almost nonexistent at another nearby. This is the case at surf spots such as Black's Beach, El Porto, and Mavericks. Knowing your break Using swell data, which is readily available on the internet, it is possible to predict how the surf will be for a fairly large area. However, the waves can differ drastically from spot to spot and from time to time. To accurately forecast the swell conditions for a spot, it is needed to understand how different conditions affect the waves there. Types of breaks The shape of the ocean floor affects the break greatly. In general there are gradual sloping ocean floors which result in a slower crumpling wave (better for long boarding) and steeper sloping floors which result in a faster, hollower breaking wave (better for short boarding). There are also many different types of breaks: Beachbreaks are the most common breaks in the world. The primary characteristic of a beach break is that the waves break over a sandbar bottom. They have many random qualities in