A marine artist, par excellence, Wyllie was also personally a keen sailor. He was Marine Painter to the Royal Victoria Yacht Club, Ryde.
Wyllie took up etching when Robert Dunthorne commissioned him for a print of the artist's painting Toil, Glitter, Grime and Wealth, exhibited at the R.A. In 1883. From 1907 he increasingly used drypoint, and occasionally in later years, aquatint, to achieve atmospheric tonal effects.
In the Temple of Poseidon, through selective wiping of the plate, he has 'spotlighted' the temple in the sun and created white highlights on the sails and flying gulls. The temple stands at the southernmost point of the Sounio peninsular, within a later fort that protects the coast of Attica.
The ancient temple was built in 440 BC, and many of its original Doric columns have survived. Lord Byron carved his name in the marble of one of these columns.