Here's another image of the productive outing I had with both species of goldeneye. This one was gliding smoothly downstream, from left to right, when it seemingly thought it saw something fishy (me lying on the ice). It immediately started to swim hard against the current (now right to left), and once past me took off in frantic flight (but angling away, thus no images taken). Although looking proud and regal, you can get a sense that it has spotted me! The cloudy lighting conditions made it a joy to expose for them.
Canon 7DII + 500mm f/4II + 1.4 TC III, manual exposure, evaluative metering, 1/1250s., f/5.6, ISO 1600, natural light handheld, pretty much full-frame, added a catchlight to liven the eye.