Every year, rip currents kill more people than hurricanes, fires and sharks. Yet a serious disconnect exists between rip current research, identification, human behavior and warnings.
Rip currents are the result of complex interactions between
waves, currents, beach slope, wind speed and direction, tides and
nearshore bottom topography. A rip current forms as the narrow,
fast-moving section of water travels in an offshore direction,
usually in a channel between two sand bars.
Sometimes rip currents are caused by human-engineered structures
such as groynes, jetties and piers. These structures often are
responsible for disrupting the natural flow of water by directing
water seaward at an accelerated rate. At these are locations,
permanent and extremely strong rip currents occur.
The strength and speed of rip currents varies greatly. This
makes them especially dangerous to inexperienced swimmers such as
tourists. Typically, rip currents range in velocity between 1 and 3
feet per second. However, recently one of us encountered a rip
current in Thailand during monsoon season with a velocity of 8 feet
To demonstrate the danger of a rip current, an Olympic gold
medal swimmer was placed in the center of a particularly strong rip
current. He was not able to swim against the current despite his
world-record swimming ability. This experiment demonstrated the
importance of teaching people about the need to swim parallel to
the beach until the current weakens before attempting to swim back
to shore. If this recommendation is not followed, it may lead to
exhaustion, panic and, in some cases, death.
One interesting observation that is beginning to emerge from our
research has to do with the relationship between drowning and the
strength of the rip current. Intuitively, we expected to find that
more drownings occur during times when rip currents are the
strongest. Not so. On days when there are strong rip currents, high
winds and large waves usually occur. These conditions discourage
most beach-goers from swimming.
When the waves and surf begin to abate, swimmers often are
lulled into a false sense of safety, not realizing that rips are
still present, but not necessarily as strong.
These relatively weak rip currents produce enough strength to
pull an unsuspecting individual out to sea. In these more moderate
conditions, most drownings seem to occur.
Some of our research involves using tracer dyes to better define
the physical characteristics of rip currents. To gain a perfect
vantage point, we sometimes hover over the beach in a helicopter.
This research is revealing some unexpected results that may suggest
the need to rethink some of the education and warning programs
currently being devoted to rips.
Most rip currents we observe do not conform to the
characteristics portrayed in warnings and that are presented in
public education programs. Typically, the classic rip current is
depicted — perfectly formed, having an identifiable feeder
and neck nearshore that develops into a head or mushroom-like
feature further offshore.
In reality, this depiction is seldom valid. In the majority of
cases, rip currents cannot be observed from the beach and, in cases
when they can be observed, they assume many different
This observation has important bearing on lifeguard practices.
It’s usually not enough for lifeguards to visually look for
rip currents from the vantage point of their beach chairs or from
standing at the water’s edge.
Instead, they must physically go into the water on a regular
basis and “feel” for rips. This should become common
practice and be included in all lifeguard manuals.
An interesting outcome of our study is the realization that
beachgoers’ knowledge about rip currents significantly varies
geographically. For example, beachgoers know more about rip
currents on Australian and California beaches than those on Florida
and Puerto Rican beaches. The reason for this finding is fairly
obvious: There are more tourists on Florida and Puerto Rican
beaches, meaning more people unfamiliar with the region or its rip
Our survey is revealing another important finding. About half of
the beachgoing public confuses rip currents with rip tides and
undertows. Rip tides represent an entirely different phenomenon
and, as most savvy experts know, there is no such creature as an
Though our study won’t be completed for at least another
two years, we’ve become aware of a serious disconnect between
rip current research and human behavior as it relates to awareness
and having accurate knowledge about rip currents.
Our research also is indicating a need to develop better and
more consistent warning signs. Despite what many experts believe,
warning flags sometimes are not effective in how they warn swimmers
about rip currents for the following two reasons: First, flags
sometimes are not changed in a timely manner to accurately reflect
water conditions. Secondly, because flags represent symbolic
language, people don’t always know what a flag means. The
public is especially confused about the meaning of a
“red” flag and a “double red” flag.
This information underscores the importance of disseminating
information that allows for the correct interpretation of the flag
colors. It also underscores the importance of consistent flag use
on different beaches. This must be done on beaches throughout the
world, not just in America.
Better and more effective rip current warnings should be developed.
But until this can happen, the ones currently in use (that is, the
flags) should be continued because something is much better than
nothing, especially on unguarded beaches. Vacationers staying at
hotels, for example, still should be warned using flags and