Sleep. 1910 Kuzma Sergeevich Petrov-Vodkin (1878-1939)

The picture has something of this: nude, shirtless, body, people, water, sea, naked, man, back, thorax, ocean, healthy, woman, beach, muscle, sand.
Perhaps it’s a painting of a man and a woman standing next to each other in front of a rocky area with a mountain in the background and a blue sky.