Check the incoming waves for regularity. Although it is normal for there to be some variation in wave patterns, a calm section between white-capped breakers may indicate the presence of a rip current. This may be quite subtle, but in more severe rip currents, a clearly calm spot between breaking waves can be seen. These occur because the rip current is forming an opposing current out to sea, tempering the incoming waves.
Look for debris in the water. If there is a rip current, a line of floating debris, such as seaweed or foam, may be drifting away from the shore rather than toward it. This may indicate a rip current because the water flowing out to sea will repel debris, preventing it from being washed in with the waves.
Look for any patches of water with a noticeably different color than the rest of the surrounding sea. A riptide can churn up algae, sand and debris from the sea floor as the water is being funneled back out to sea.
If at all possible, get to a high vantage point near the shoreline. The symptoms of rip currents are most visible when seen from above. Having an elevated view of the shore can also help to see the shallow parts of seabed, which is where rip currents are most likely to form.
