UFO appears near the coast of Costa Rica

On October 15, 2014, during a cruising off Costa Rica, a tourist taken photos of the immense ocean. On site, nothing has been seen. But when he is gone home, he noticed a spherical UFO on only one image. What is it?

Witness report:

After departing Limon, Costa Rica on October 15, 2014, on the Coral Princess bound for Jamaica, my wife and I were on our balcony taking pictures of the sunset. My wife was using our digital camera, a Sony DCS-H50 Cybershot. She took several pictures, then left the balcony and we went to dinner. When we got home and looked at the pictures on our computer screen, picture DSC05685 (taken at 6:03 pm Eastern Daylight Time) showed what appears to be a round object racing through the clouds in the upper left quadrant. The picture before taken the same minute shows nothing in that area except clouds and the picture taken after at 6:07 pm also shows nothing.