Marine probably dates from 1899 or 1900.

Marine, Private Collection

The Shore, Pourville, Ashmolean Museum

The fluid brushstrokes on the deep green sea, and the drier strokes on the bright grey and blue sky, suggest this date. It is dated from the technique and butterfly, which are similar, for instance, to The Shore, Pourville [YMSM 521]. It may therefore have been painted while Whistler was in Pourville in the summer of 1899.