This is not really marine art - the Atter-see is a large lake, not salt water (German 'see' is not exactly the same as English 'sea'). But then Klimt can't be blamed for living in a landlocked country. A great evocation of an expanse of water through minimalist composition in a square format.
Island in the Attersee
If you are on to a great idea - do another version of it.