Why The Diana Nyad Skeptics Think Her Historic 110-Mile Swim Was Fraudulent

In the wake of 64-year-old Diana Nyad completing her life-long dream of swimming the 110 miles between Cuba and Florida, some hardcore open-water swimmers are saying she had to have cheated.

The criticism is mainly coming from some people on a MarathonSwimming.org message board.

Based on GPS data that showed a spike in average speed during the middle portion of her swim, commenters believe that Nyad didn't swim the whole way, and perhaps even rode on her support boat for a few hours.

Nyad and her team deny those accusations, and say the speed boost was caused by a rare and beneficial confluence of ocean currents, which scientists agree could have helped her double her average speed.

A Marathon Swimming commenter named Andrew Malinaka (an open-water swimmer himself) has spearheaded the movement to analyze the authenticity of Nyad's swim.

Using an application called Firebug, Malinaka ripped a bunch of code and GPS coordinates of Nyad's website to make this map of the route she took. The yellow line is her path from Havana to Key West, and she went from south to north:

Using hundreds of GPS data checkpoints from Nyad's website, another commenter put together a graph of her average speed by hour. As you can see (below), her speed more than doubled from her original pace when she hit the 30-hour mark.

The skeptics say that this dramatic and sustained increase in speed followed by a return to her original pace at the end of the swim is suspicious.

Nyad didn't have her crew take continuous video during the 53-hour swim, and didn't have independent media on her support boat. In addition, commenters claim that the independent observers who verified her swim were biased because they had prior relationships with Nyad, which everyone involved denies.

Because of that, Nyad is at an inherent disadvantage when trying to explain the hump in the middle of this top graph:

Looking at this data, Malinaka wrote:

"So reading this graph, I'm asked to believe that Diana swam 27 hours at her normal pace, picked up some speed the first morning as the Gulf Stream moved in her favor (that's what her diary says), and then BAM! nearly triples her speed as she begins complaining about lung discomfort. She holds an amazing pace for the next seven hours, through the second night's squall with shark divers flippering their fastest to keep up with this rocketing swimmer until dawn, and then...we're back to a nice normal pace as the sun rises on her final day."

To answer Malinaka's question, that's exactly what he's supposed to believe.

Nyad, her team, and even an independent oceanographer say the speed increase was due to lucky currents. Nyad's team did not immediately respond for comment, but she told the New York Times, "We were definitely traveling north at a faster speed than what I can do on my own. I just got lucky."

Typically, the currents in that area of the Gulf go more east-to-west than south-to-north.

But on that day, the current shifted along Nyad's exact path (southeast-to-northeast) and basically put her on a conveyer belt toward Florida.

An oceanographer from Australia looked into the data after someone e-mailed him to ask if Nyad was lying, and he says the currents really were crazy that day. He told the Guardian:

"Many times that current runs west-east and you're constantly fighting the current if you're swimming north. In this case, it was in the shape of an S, and the angle was almost exactly from Havana to Key West."

This is what the currents are like today. You can see that it's going west-to-east, as opposed to south-to-north, and could have made things really tough for Nyad:

There's no hard evidence that Nyad cheated.

The so-called "smoking gun" for the MarathonSwimming.org people - the sustained increase in average speed for a 12-hour span in the middle of the swim - can be explained by current conditions that scientists say occurred on that day. Their other claims - that Nyad's handlers helped her eat and put cream on her body - having more to do with open-water swimming snobbery than actual cheating.

If the skeptics are going to successfully discredit her swim, they need some concrete evidence.