The floor of the Pacific Ocean in Stillwater Cove near California's Pebble Beach Golf Links, which is hosting the US Open this week, is littered with golf balls.
The balls easily find their way into the water as the course sits directly on the Pacific Ocean.
The environmental problem was first identified three years ago by Ms Alex Weber, 19, while she was diving in California. She discovered something she had never seen before - a white sea floor.
"It was just blanketed in this mess of golf balls," she told Reuters.
Ms Weber connected with a researcher at Stanford University, and they went on to publish the first paper about golf ball marine pollution, which got the attention of the officials at the course.
The balls are bad for the environment because they break down into smaller shards of plastic, which are eaten by marine life.
"They contribute to the microplastics problem, getting into the food chain and ultimately into us," she said.
In February, the Pebble Beach Company agreed to conduct around 200 underwater cleanups every year for five years, or until a "dramatic shift" is seen in the underwater environment.
The company is also posting signs to alert players to not hit into the water, and sending divers to help collect any errant balls.
"We had no idea what it would become when this started," said Ms Weber. "It is all coming together."