It looked like snot

Swimming in syrup is as easy as water by Michael Hopkin:

It's a question that has taxed generations of the finest minds in physics: do humans swim slower in syrup than in water? And since you ask, the answer's no. Scientists have filled a swimming pool with a syrupy mixture and proved it.

"What appealed was the bizarreness of the idea," says Edward Cussler of the University of Minnesota, Minneapolis, who led the experiment...

while you experience more "viscous drag" (basically friction from your movement through the fluid) as the water gets thicker, you generate more forwards force from every stroke. The two effects cancel each other out.

via geekpress.