Rip currents, riptides and undertow have different names because they're different phenomena. Rip currents are strong, narrow jets of water that move away from the beach and into the ocean. They can flow quickly, typically around 5 miles (8 kilometers) per hour; they aren't predictable and are a result of the shape of the coastline. A riptide is caused by the moon's gravitational pull and is a predictable rise and fall of the water level. Undertows are currents that pull you underwater to the bottom of the ocean.
Are there questions about the oceans we haven't thought to ask?
Answered by Bruce Robison
What makes a rogue wave rogue and how do they form?
Answered by Planet Green
What should U.S. policy on the oceans be?
Answered by Robert B. Gagosian and Julie Packard