Such currents can all be extremely dangerous, dragging swimmers away from the beach and leading to death by drowning when they attempt to fight the current and become exhausted.
Surviving an encounter with a rip current
It is important to never attempt to fight a rip current. One should always swim parallel to the shoreline. If you see a person caught in one, yell at them to do so. This removes the swimmer from the current, which typically occurs most strongly between sandbars. Floating until the current disperses into deeper waters is also another method of surviving such a dangerous incident, but it may leave the swimmer farther out from shore.
Avoiding the shore when surf is rough (such as during high onshore winds, or when a strong hurricane is far offshore) is an advisable safety measure, as this is when very strong tides or currents are most prevalent. Posted warnings, where available, should always be heeded.