The best most screen actors can hope for in their dotage is roles that don’t embarrass or seem beneath them.

The lucky ones land a decent scripted series or a challenging supporting role on the big screen. But too many keep their hands in via inferior piffle — scripts with no ambition, edge or point other than as a make work project for elderly stars.

Michael Douglas has turned up in a few of those — too many. But “Looking Through Water” gives him a chance to play a grand old man with a colorful life behind him and a troubled grandkid to tell it to. And he delivers.

It’s no stretch, and the script suggests the Bob Rich novel it’s based on traffics in sentimental cliches and tropes and tropical Belize settings and nothing more. But Douglas and fellow screen veteran David Morse have moments of gravitas and reflection and nobody on camera lets down the side.

Douglas is the aged, rich but laid-back fisherman/grandpa who picks up troubled grandson Kyle (Walker Skobell) after he’s lost a fistfight and fresh off his latest mouth-off with his at-a-loss mom.

The kid’s a mouthy 14 year-old, given to calling his parents and his grandfather by their first name. Gramps rows Kyle across a tranquil New England lake in his Whitehall skiff and tries to get the story of the kid’s fight out of him. So he talks about the pivotal moments from his high-flying past.

Younger William (Michael Stahl-David) was CEO of the family business, engaged to be married a second time and in the process of being honored at some “Greed is Good” era New York Chamber of Commerce function when he blew it all up. With cause.

Next thing he and we know, he’s jetting off to ’80s Belize for a father-son fly-fishing tourney, with his estranged rich drop-out Dad (Morse) and Dad’s fishing guide Cole (Cameron Douglas).

A little “time on the water” might cure what ails our CEO trying to fend off a hostile takeover by a former friend who cheated with his fiance and plans to steal the company. First, William has to give himself over to fly-casting and give up the brick phone.

“Proving things is a young man’s game,” weathered, wizened father Leo tells him.

Dad smokes, drinks Belikin out of the bottle and tries to get his adult son’s priorities straight, a story the son later relates to his grandson with similar intent.

No, the two life experiences have nothing in common that makes this relatable, but just go with it.

There are a couple of grace notes that give this “A River Runs Through It Lite” tale a touch of humanity, if not poetry. Morse is as grand at playing “the old man” as Douglas, and fits right in with the local Belizian color.

But this script is strictly paint-by-numbers “pretty.” There’s the medically-trained local cutie (Ximena Rojo) who catches William’s eye, the seasoned seaside bar owner (Tamara Tunie) who knows more than she imparts to the new gringo in town, and Michael’s son Cameron Douglas gives some over-tattooed grit to overtanned fishing guide Cole.

It’s all pre-digested because we’ve seen everything that happens here before and heard every pearl of wisdom dropped in a dozen too-too similar films in recent years.

It’s a movie where literally every scene has a punch line we see coming and every introduction sets up a relationship painted in via strokes we’ve seen a hundred times before.

But “Looking Through Water” passes the time even if it never quite surprises in any way that makes it “play.”

Rating: TV-14, fisticuffs, sexual situations, smoking and alcohol use, profanity

Cast: Michael Stahl-David, David Morse, Ximena Rojo, Cameron Douglas, Tamara Tunie, Walker Skobell and Michael Douglas.

Credits: Directed by Roberto Schneider, scripted by Zach Dean and Rowdy Harrington, based on a novel by Bob Rich. A Good Deeds release on Amazon Prime.

Running time: 1:48