Currents on reefs
With all the waves crashing in over the reefs, be it low or high tide, the water has somehow to flow out of the basin again. So it does through slightly deeper channels ("Passe") here and there on the reefs. Our experience was that these were well marked by warning signs: "Dangerous swimming", "Swimming prohibited" etc. on land. However, several tourists seemed not to understand this danger: the force of the current in addition to the ocean breakers' backwash may drag even superb swimmers into the deep outside the reef. It could be hard to reenter the lagoon without being lacerated by coral outcrops.
