jetty A type 2 jetty occurs in an ebb-tidal delta, a delta transitioning between high and low tide. This area has shallow water, refraction, and distinctive seabed shapes that create large wave heights. An example of a type 2 jetty is called "The Poles" in Atlantic Beach, Florida. Atlantic Beach is known to have flat waves, with exceptions during major storms. However, "The Poles" has larger than normal waves due to a 500-meter jetty that was installed on the south side of St. Johns. This jetty was built to make a deep channel in the river. It formed a delta at "The Poles". This is a special area because the jetty increases wave size for surfing when comparing pre-conditions and post-conditions of the southern St. Johns River mouth area. The wave size at "The Poles" depends on the direction of the incoming water. When easterly waters (from 55°) interact with the jetty, they create waves larger than southern waters (from 100°). When southern waves (from 100°) move toward "The Poles", one of the waves breaks north of the southern jetty and the other breaks south of the jetty. This does not allow for merging to make larger waves. Easterly waves, from 55°, converge north of the jetty and unite to make bigger waves. Type 3 jetty A type 3 jetty is in an ebb-tidal area with an unchanging seabed that has naturally created waves. Examples of a Type 3 jetty occurs in “Southside” Tamarack, Carlsbad, California. Type 4 jetty A type 4 jetty is one that no longer functions nor traps sediment. The waves are created from reefs in the surf zone. A type 4 jetty can be found in Tamarack, Carlsbad, California. Rip currents Rip currents are fast, narrow currents that are caused by onshore transport within the surf zone and the successive return of the water seaward. The wedge bathymetry makes a convenient and consistent rip current of 5–10 meters that brings the surfers to the “take-off point” then out to the beach. Oceanographers have two theories on rip current formation. The wave interaction model assumes that two edges of waves interact, create differing wave heights, and cause longshore transport of nearshore currents. The Boundary Interaction Model assumes that the topography of the sea bottom causes nearshore circulation and longshore transport; the result of both models is a rip current. Rip currents can be extremely strong and narrow