Ravensburger’s “Circle of Colors — Ocean”. 500 pieces.
FWIW, 64 “border” pieces. I counted the number of pieces around the circumference because I was curious how much “arc” there might be for the average border piece. Dividing 360° by 64 and the average arc to each piece at the edge of the puzzle is only 5.6° (0.098rad). That covers a pretty small angle.
Retired economics professor (“dismal scientist”). Married 45+ years to the love of my life; we have two grown daughters, both married, two granddaughters and a...