I’ve seen this little diving duck a number of mornings at Niles Beach. At first I thought it was a juvenile eider, but it is too small and dives differently than eiders. It has a long spear of a tail feather, which you can see in the first and last photos. It may be a juvenile of its kind, but I have no idea what it is. It spends very little time above water and a long time under so it was challenging to shoot. Does anyone know what it is?