Along Tsiribihina, a river flowing from Madagascar in the Mozambique Channel by a delta, Madagascar, Indian Ocean, Africa

Masonic symbols of angle bracket and delta at the Human Right Monument in the Paris Champ de Mars, Paris, Ile de France, France, Europe

Along Tsiribihina, a river flowing from Madagascar in the Mozambique Channel by a delta, Madagascar, Indian Ocean, Africa

Freshwater lake and sand dunes at Ilha Grande de Santa Isabel, Parnaiba River delta, Piaui, Brazil, South America

Freshwater lake and sand dunes at Ilha Grande de Santa Isabel, Parnaiba River delta, Piaui, Brazil, South America

Freshwater lake and sand dunes at Ilha Grande de Santa Isabel, Parnaiba River delta, Piaui, Brazil, South America

Sand dunes at Ilha Grande de Santa Isabel, Parnaiba river delta, Piaui, Brazil, South America

Vegetation on a lake at Ilha Grande de Santa Isabel, Parnaiba river delta, Piaui, Brazil, South America

Lake and sand dunes at Ilha Grande de Santa Isabel, Parnaiba River delta, Piaui, Brazil, South America

Lake and sand dunes at Ilha Grande de Santa Isabel, Parnaiba River delta, Piaui, Brazil, South America

In Fangar Bay mussels and oysters are farmed. Ebro Delta Nature Reserve, Tarragona, Catalonia, Spain.

Men collecting mussels. In Fangar Bay mussels and oysters are farmed. Ebro Delta Nature Reserve, Tarragona, Catalonia, Spain.

Worker shows mussels dead due to heat wave. In Fangar Bay mussels and oysters are farmed. Ebro Delta Nature Reserve, Tarragona, Catalonia, Spain.

Men working in mussel farming. In Fangar Bay. Ebro Delta Nature Reserve, Tarragona, Catalonia, Spain.

Aerial view of marshes, the Tancada lagoon, rice fields, Eucaliptos beach and lﾴAlfaca beach; Sant Carles de la Rapita, Ebro Delta, Natural Park, Tarragona, Spain

Freshwater lake and sand dunes at Ilha Grande de Santa Isabel, Parnaiba river delta, Piaui, Brazil

Aerial Photo, Delta of Rio Parana, Estuary in the Rio de la Plata, Buenos Aires, Argentina, South America

Thunderstorm in the Mediterranean off Tarragona the night of August 9-10, 2016, Sant Carle de la Rapita, Ebro Delta, Tarragona, Spain

Thunderstorm in the Mediterranean off Tarragona the night of August 9-10, 2016, Sant Carle de la Rapita, Ebro Delta, Tarragona, Spain

Thunderstorm in the Mediterranean off Tarragona the night of August 9-10, 2016, Sant Carle de la Rapita, Ebro Delta, Tarragona, Spain

Thunderstorm in the Mediterranean off Tarragona the night of August 9-10, 2016, Sant Carle de la Rapita, Ebro Delta, Tarragona, Spain