Sand trucks line an area where runners will line up for security screening before the start of the New York City Marathon in New York, U.S., November 5, 2017. REUTERS/Lucas Jackson 

A man relaxes on Sao Bento beach at Guanabara Bay, which receives waters from polluted rivers in Rio de Janeiro, Brazil, July 30, 2015. Rio de Janeiro continues to face criticism locally and abroad that the bodies of water it plans to use for competition in the 2016 Olympic Games are too polluted to host events. Untreated sewage and trash frequently find their way into the Atlantic waters of Copacabana Beach and Guanabara Bay - both future sites to events such as marathon swimming, sailing and triathlon events. Olympic sailors are not worried about getting sick during the Rio Olympics next year in spite of reports that waters where the sailing events will take place have pollution levels equivalent to raw sewage, competitors told Reuters on Thursday. REUTERS/Sergio Moraes 

Rubbish is pictured at Fundao beach, on the banks of the Guanabara Bay, in Rio de Janeiro, Brazil, July 30, 2015. Rio de Janeiro continues to face criticism locally and abroad that the bodies of water it plans to use for competition in the 2016 Olympic Games are too polluted to host events. Untreated sewage and trash frequently find their way into the Atlantic waters of Copacabana Beach and Guanabara Bay - both future sites to events such as marathon swimming, sailing and triathlon events. Olympic sailors are not worried about getting sick during the Rio Olympics next year in spite of reports that waters where the sailing events will take place have pollution levels equivalent to raw sewage, competitors told Reuters on Thursday. REUTERS/Sergio Moraes 

A piece of a toy doll is seen on Fundao beach in the Guanabara Bay in Rio de Janeiro, Brazil, July 30, 2015. Rio de Janeiro continues to face criticism locally and abroad that the bodies of water it plans to use for competition in the 2016 Olympic Games are too polluted to host events. Untreated sewage and trash frequently find their way into the Atlantic waters of Copacabana Beach and Guanabara Bay - both future sites to events such as marathon swimming, sailing and triathlon events. Olympic sailors are not worried about getting sick during the Rio Olympics next year in spite of reports that waters where the sailing events will take place have pollution levels equivalent to raw sewage, competitors told Reuters on Thursday. REUTERS/Sergio Moraes 

A damaged sofa is pictured on Fundao beach at Guanabara Bay, which receives waters from polluted rivers in Rio de Janeiro, Brazil, July 30, 2015. Rio de Janeiro continues to face criticism locally and abroad that the bodies of water it plans to use for competition in the 2016 Olympic Games are too polluted to host events. Untreated sewage and trash frequently find their way into the Atlantic waters of Copacabana Beach and Guanabara Bay - both future sites to events such as marathon swimming, sailing and triathlon events. Olympic sailors are not worried about getting sick during the Rio Olympics next year in spite of reports that waters where the sailing events will take place have pollution levels equivalent to raw sewage, competitors told Reuters on Thursday. REUTERS/Sergio Moraes 

A piece of a toy doll is seen on Fundao beach in the Guanabara Bay in Rio de Janeiro, Brazil, July 30, 2015. Rio de Janeiro continues to face criticism locally and abroad that the bodies of water it plans to use for competition in the 2016 Olympic Games are too polluted to host events. Untreated sewage and trash frequently find their way into the Atlantic waters of Copacabana Beach and Guanabara Bay - both future sites to events such as marathon swimming, sailing and triathlon events. Olympic sailors are not worried about getting sick during the Rio Olympics next year in spite of reports that waters where the sailing events will take place have pollution levels equivalent to raw sewage, competitors told Reuters on Thursday. REUTERS/Sergio Moraes TPX IMAGES OF THE DAY

A toy doll is seen on Fundao beach in the Guanabara Bay in Rio de Janeiro March 13, 2014. According to the local media, the city of Rio de Janeiro continues to face criticism locally and abroad that the bodies of water it plans to use for competition in the 2016 Olympic Games are too polluted to host events. Untreated sewage and trash frequently find their way into the Atlantic waters of Copacabana Beach and Guanabara Bay - both future sites to events such as marathon swimming, sailing and triathlon events. REUTERS/Sergio Moraes (BRAZIL - Tags: ENVIRONMENT SPORT OLYMPICS) 

A competitor runs in the Singapore Marathon while runners for the 10 km race wait for the start of their race in Singapore December 5, 2010. The Marina Bay Sands Casino (R) and the Singapore Flyer Observation Wheel are seen in the background. REUTERS/Tim Chong (SINGAPORE - Tags: SPORT ATHLETICS) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

A competitor runs on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitor run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

A competitor runs on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon, or the Marathon of Sands, in Merzouga in the southern Moroccan Sahara, near Er-Rachidia, March 30, 2008. The Marathon of Sands is a race with the reputation of being the most difficult in the world. REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

A competitor gestures during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

Children run with competitors during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

Competitors run during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

Competitors run during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

Competitors run on the dunes during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

Competitors pass a lizard during the Les Sables Marathon or The Marathon of Sands in Rissani, southern Moroccan Sahara, near Er-Rachidia, March 25, 2007. The Marathon of Sands is a race with the reputation of being the most difficult in the world.
REUTERS/Rafael Marchante (MOROCCO) 

Argentina's Cabrera hits out of a sand trap on the 18th green at the Player's Championship of Europe in Alveslohe. Argentina's Angel Cabrera hits out of a sand trap on the 18th green during playoff round at the Player's Championship of Europe at Gut Kaden in the northern German village of Alveslohe near Hamburg July 24, 2005. Sweden's Niclas Fasth won his second title of the season by edging out Cabrera in a playoff after a marathon finish to the Players Championship of Europe on Sunday. REUTERS/Christian Charisius