Dangerous conditions: a rip.

A rip or tip-tide is a current of water moving in a seaward direction. It is formed by the movement of the waves as they pound onto the beach in a sideways motion. This displaces and pushes other parts of the water back out to sea. A rip is a dangerous condition because it can swiftly carry objects - including swimmers - out to the deeper part of the ocean. If you are not a strong swimmer, avoid entering the water during rip conditions. If you do get caught in a rip and are unable to free yourself from its grasp, lifeguards will be able to rescue if you signal to them - or to others nearby - that you need help.