In this surprisingly non-blurry video made by a group of Swedes out for a pleasure ride on the Baltic, the "F" in UFO stands for "floating." A white globe seems to be chasing their ship, matching its speed and totally unimpeded by currents from the ship's wake (its behavior also eliminates the possibility that the object is tethered to the boat).
As you can see in the video, the UFO seemed to be focused on the boat for a while and then veered off in another direction. We have no explanation for the object, though officials in Sweden speculate that it might be part of a science experiment or connected with a submarine. My hope is that it's a new robot made by somebody who will publish a how-to article on it in the next issue of MAKE magazine. I want my zoomy, creepy sea orb robot!