Papa Joe Simpson -- Makes Hot Young Man His Beach

Jessica Simpson's dad Joe has found a young man to spend his time with ... and photograph ... shirtless ... in Miami.

The pics were taken Saturday in South Beach, showing 55-year-old Joe getting his tan on with a much younger man ... and then taking shirtless photos of the guy, sprawled out on the sand.

Joe divorced ex-wife Tina in April after 35 years of marriage.

Whatever ... looks like he's having fun.