(CNN) Dressed in a glistening wetsuit, and sitting behind the wheel of a golf cart, Sam Harrison admits he looks like the most absurd fish out of water you've ever seen.

Get him in a lake, however, and the 22-year-old is a real-life treasure hunter with the instinct of a shark, able to uncover his prey in zero visibility and sub-zero temperatures.

In this case, the prey is golf balls. And with an estimated 300 million of the wayward white orbs lost in the U.S. alone each year, there is serious money to be made from their recovery -- if you're willing to take the plunge.

Imagine swimming in a milkshake of silt. Now add weeds, broken bottles and every type of critter from leeches, to water snakes, even crocodiles, and you've pretty much got the idea of the perils of golf-ball diving.

Making money from misfortune

For even the world's best golfers, one of the most fearsome holes in sport will rear its watery head this week at the prestigious PLAYERS Championship in TPC Sawgrass, Florida -- the infamous 17th hole.

The "Island Green," as it is known, is a peninsula measuring just over 120 meters, completely surrounded by water. It's a nightmare for players, and a potential gold mine for golf-ball divers.

The precariously placed 17th hole at TPC Sawgrass, Florida, has claimed many victims over the years.

But for those unable to plunge the depths of Sawgrass' bountiful lakes, is the job of golf-ball diving really worth the effort?

"On average, you'll find 5,000 balls per lake," says Harrison, who -- when not taking a leap of faith on Britain's golf courses -- can be found working as a banker in London.

"Say we're selling the balls we find at an average 50p (75 cents)," explains the co-founder of Lake Ball Diving . "That would give us £2,500 ($3,700)," said Harrison, estimating that in a year he could earn up to £100,000 ($150,000).

It's a similar story in America, according to Paul Lovelace, who has been diving for "white gold" over the past three decades.

"I think everybody has a dream of diving for sunken treasure -- and that's basically what we're doing every day," says the 54-year-old owner of Golf Ball Paul's, who previously worked as a search-and-recovery diver on offshore oil rigs.

"It's the thrill of the hunt."

The fairest of them all: The Titleist Pro V1 golf ball is a prize catch for divers.

The most prized catch of all is the Titleist Pro V1. Pluck a bagload of these premier balls from the bottom of a sludge-filled lake, he says, and you know it's a good day.

"A perfect Titleist? You can retail that for $2," says Lovelace, speaking by phone from his Kansas warehouse, stacked high with bulky sacks of balls waiting to be washed and sorted for sale.

But even before he or Harrison hit the water, there are significant outlay costs. On both sides of the pond (in this case, the Atlantic Ocean,) golf courses charge divers between 7-10c per ball they find. And that can quickly add up to hundreds of dollars.

Nature calls

Once in the water, you're lucky to see more than a foot in front of you, and Lovelace has one piece of advice for new divers: "If you're grabbing stuff down there and it's not round -- don't pick it up!"

"In the Midwest we have snapping turtles, and they can take off fingers and hands and toes and other extremities if you're not careful."

In some parts of the U.S., divers have the added danger of alligators, such as this one at the Zurich Classic of New Orleans.

In the UK, Harrison often comes face to face with water snakes. "Sometimes you rough up the reeds and you can see one of them swimming towards you," he says, adding that he's usually face-down in pitch black darkness with nothing more than a fog light and a rake.

But perhaps more worrying is the water itself. "On some courses, the lakes are more like sewers," he says. "In those stagnant pools you can catch diseases, so you have to wear a head guard, a bit like an all-in-one wetsuit, so nothing can get on you."

One man's trash

The bizarre array of objects buried at the bottom of a lake tell of woe on the sporting field. Not just the odd golf club hurled in anger, but entire bags -- and even a motorized cart -- have been found by divers.

If you're getting into this messy business because you enjoy scuba diving in tropical locales, you better think again, says Harrison.

"Don't get me wrong, I'd much rather be diving in the Red Sea, seeing some picturesque fish than broken beer bottles," he says.

"But overall I generally enjoy it. And you never know," he adds, "you might find a lake where you hit the jackpot."