Viewed from the Black Oak Road viewing platform, in fading light.
A fairly graceful-looking diver with a slender dagger-shaped bill, rounded back of head / neck and a slight bulge on forehead. Head a shade lighter than dark back, darker lores, dark vertical stripe down centre of otherwise clear white front of neck. Strong contrast between white cheeks and dark cap, and between dark back of neck and pale front of neck, with no half-collar. Pronounced white flank stripe always visible, usually (but not always) with larger white flash at rear of flank. Fairly uniform back with slight scalloping pattern.