38 year old son-in-law, 12 year old grandson, and myself (63 year old male) were fishing on my back yard dock in Cape Coral, Florida at about 10 pm. My grandson said, "what's that in the sky?" We all observed a strobing pinpoint of light at extreme altitude (much higher than most commercial airline flights) at about 45 degrees of elevation in the ESE, flying generally in a northerly direction. It was moving at a very fast, though fixed, speed and strobing in a regular tempo. During the 10 seconds or so that we initially observed it, it transversed maybe 5 degrees of arc. (That was extremely fast considering it's apparent altitude). It suddenly disappeared. There were scattered clouds that night and I initially thought the clouds had obscured it. Less than 10 seconds later, my son-in-law shouted "there it is!" and we observed it a full 30 to 40 degrees north (yet still in line of flight) of where we had initially seen it. It was like it had skipped instantly over many many miles. Very strange. I do not believe this was an airplane nor a satellite. If my estimates of elevation and trigonometric calculations are correct, this thing covered at least 5 miles in 10 seconds from the time it disappeared until it reappeared. Previously, it seemed to be moving exceptionally fast, but the speed at which it jumped forwards during the few seconds it was invisible seemed impossible. All three of us observers thought this sighting was exceptionally strange. When we described this to other family members, we endured some good-natured teasing and derision.