the lifeguards signal dangerous underwater currents via red flags on the beaches - many visitors interpret the red flags as only referring to the strength of the waves, but in fact the danger can often be hidden in the undertows.

generally, in rio de janeiro waves are strong and great for surfing all year long, with the best period being the autumn and the winter - with east to south-west winds, waves are typically tubular, ranging in size between 1 to 2 meters.

oceanic beaches in rio de janeiro are populated by a wealth of marine life - mostly invisible to people staying on the shore, much of it can be seen by scuba divers.