Coming back from Dering Harbor through the Plum Gut to Old Saybrook. Thinking boy, that's odd, can usually see Connecticut long before now. Nice and Sunny. About 3 miles from shore, wham. white nothingness. Slowed to 6 kts, fired up the radar and set the gps. Nothing like seeing targets on radar close, dead ahead and not seeing them with your eyes. One sail boat just seemed to materialize. Approaching Saybrook breakwater, radar is all scatter but still couldn't see it. Another boat and I trying to find the entrance. Heard the fog horn slightly to the right. Was 100' from the lighthouse before seeing it. Closest I ever got to a lighthouse without seeing it first.