My friend natalie and i were walking through nantucket, we flew their with some friends, i am a pilot and we make trips like this every once in a while. While we were walking around we saw something on the horizon maybe 4.5 to 5.5 miles off of the shore. it was at about 1000 ft when i first saw it, i thought it was an airplane heading towards us- hence the left side being lighted green and the right side being lighted red with a white light on top of it. suddenly it took off up to somewhere around 7-8000 feet. it hovered there for a few seconds then it slowly lowered down to sea level and appeared to disappear. It appeared as though it entered the water, I thought about the other possibility being that it quickly flew over the horizon away from us but i find that much less likely. The object obviously appeared to be bending light around it and had a vibrating like appearance to it making it appear fuzzy. It made a very distinctive noise however not engine noise that you would expect from a manmade object- it was the sound of the air moving around the object almost like the sound of a large plane gliding without engines, I fly large rc airplanes that are electric and the sound that they make when they glide very fast is smiler to the sound that this object was giving off. The object was very easy to see and clearly identifiable if one were to look in the right direction. I told my friend natalie who was holding my iPad to record it. It was very easy to see in person, but on the video playback it is very hard to make out. I honestly feel as though it used some kind of technology that made it hard to record or see during playback. Im a pilot and strange airplanes, fighter jets, flares, chaff and all of those things i am accustomed to seeing, however this was nothing like anything I’ve seen before as far as its behavior goes. If you would like, call me if you want the video, you can barely make out an object that is a bluish color and it appears to be faintly flashing. the video would need to be optimize if you’d want actual footage of the object it was recorded on an iPad. When the iPad tries to look up a little bit, that is when the objects ascends upward, don’t mistake the light posts for it.