Rip currents:
These currents only occur when there is wave action and can be particularly prevalent at headlands and adjacent to reefs or between sand bars.
The following videos will show you how to recognize them, also how to escape them if you get caught in one. Surfers and lifesavers use these for fast and easy access to quickly get beyond the breaking waves.
Video 1 This is a very informative video. (Credit: Surf Life Saving Australia)
Video 2 Shorter less detailed. (Credit: Lifesaving USA)

Inshore holes and gutters:
These are created when waves are breaking directly at the shore, they are also generally accompanied by lateral currents or "sweeps" that run parallel to the shore and flow into a rip current, these can be especially dangerous to small children, as they can be quickly out of their depth right at the shoreline.