When the waters off Tobago develop visible lines and turn dark and cloudy, experienced sea folks know from one look that the weather has been bad, more than a 100-miles away, in South America.
Divers are particularly cautious going through the vertical divisions called haloclines that may alternate between milky green, pale blue and heavy brown. Given the poor visibility at some levels, they stay close in the fast-moving currents and far away from treacherous shoals, reminded by their watchful guides of the standard one-minute search pattern in case of separation.
Bearing mud and sediment discharged from the rain-swollen Orinoco and Amazon Rivers, noticeable plumes spread across in the dominant Guiana Current, reaching the shores of the island and its bigger sister Trinidad, and far out into the Atlantic Ocean.