The Golf Locker Room
It would take 4 miles of walking to reach all 18 holes of a regulated golf course.

Generally, playing on a regular golf course with 18 holes will make you walk anywhere between 3 to 6 miles long. However, simply walking to the next location won’t be the only kind of walking players will do in the span of a game.
Often, a player’s total walking distance increases with locating lost balls and the overall range of the course.
How many calories are burned player golf during a round, though, depends on a number of factors that the golfer controls. The biggest factor determining how many calories a golfer burns in a round of golf is the choice to walk the course or ride in a cart.
“I knew what I was getting into when I chose golf. Hell, I knew I'd never get rich and famous. All the discrimination, the not being able to play where I deserved and wanted to play - in the end, I didn't give a damn. I was made for a tough life because I'm a tough man. And in the end, I won: I got a lot of black people playing golf.”
If a golfer choose to walk while playing golf -- either nine holes or 18 holes -- they're going to burn a substantial number of calories.
The golf industry likes to say that a golfer will burn as many as 2,000 calories playing golf if they walk all 18 holes while carrying a golf bag -- which is usually 20-30 lbs. -- on their back. Effectively, walking a round of golf is like taking a 4-5 mile hike while backpacking. It's a lot of work!
During the course of a nine-hole round, which is typically 2-2.5 hours of time, a golfer could burn anywhere from 600-1,500 calories, depending on their weight, the weight of their bag, the topography of the golf course (how many hills and ups-and-downs there are). For an 18-hole round of golf, which can run from 4-5.5 hours, a walking golfer can burn anywhere from 1,200-3,000 calories.