While walking my dog an object appeared 200'-300' from me just over tree top height moving over the homes as i stood with my dog in our side yard. there was absolutely no sound coming from this craft. i was shell shocked because it was close to me and if it had been any conventional craft aside from a glider i would have heard it quite easily. it passed through my field of vision in 10 seconds or so and i lost sight of it behind roof tops across the canal. it was so close that i literally couldn't believe my eyes and i wondered should i go get my phone camera but thought if it did reappear it would do so too quick for me to get the camera and have a second shot at seeing it. i stood there for a moment looking at the gaps between roof tops hoping for a second view and i was lucky enough to see it again. at that time i caught the view of another lighted craft (presumably a helicopter) from the west heading directly for the craft. this happened in seconds as it went back behind the next roof peak. then literally seconds later the object had evidently made an incredibly quick turn outside my field of view and reappeared heading south at the same altitude and moving away from what did turn out to be a helicopter i assume, that apparently was following the craft south. this would have all been at the mouth of the chattahoochee river and the gulf of mexico area near the sanibel bridge.