You might love a restaurant, dine there once a week and greet the chef by his off-color nickname. But you don’t know a restaurant until you’ve seen the back room. The windowless office, the produce-packed cooler, the zoned-out cooks skinning an infinite pile of chicken breasts so that well coiffed waiters can conjure plate after plate as if from thin air.

Likewise, you might love Houston, but you don’t know Houston until you’ve seen its port. In all likelihood, the languid channels gouged from Buffalo Bayou once bore the drywall in your house and the gas in your car. If you bought a Volkswagen in town, that’s where it arrived.

Houston remains proudly industrial. It’s still a city that actually makes stuff, and it hasn’t shied from the gritty back-room work of refining fuel and handling more cargo than all but one port in the United States so we can keep filling up our tanks and buying what we want without giving much thought to how it got here.

Set amid this rust-streaked industrial setting, I admit it’s a bit tough to make the case for the port authority’s free boat tours as a fun outdoor family outing.

Yet it is. So much so that the 10 tours each week often welcome the maximum 100 passengers aboard the M/V Sam Houston for a ride that lasts 1 1/2 to 2 hours. The trip requires reservations in advance, a photo ID and a healthy sense of direction to find the departure point among the East End’s maze of roads, train tracks and warehouses.

I joined a few dozen kids, seniors, businessmen and European tourists boarding the ship Thursday afternoon near a worn railroad bridge that marks where Buffalo Bayou turns from an urban river to a thick vein of commerce. After a few announcements (no cameras allowed, yes, there are bathrooms, and everyone gets a free soda on the way back), our laid-back tour guide comes on the PA to point out the different types of ships and businesses we pass.

In a charming example of Houston’s no-zoning quirkiness, one of the first is Brady’s Landing – an upscale restaurant and popular wedding spot overlooking the ship canal.

Nearby, 584-foot-long U.S. transportation department ships stand at the ready, should they be needed to haul freight in the event of war or a disaster. Stacks of crushed cars pile high next to the stacks of pulverized metal they will become while flashy stainless steel clatters into a barge from the grip of a giant claw.

The voice from the intercom points out ships from Liberia, Turkey and Cyprus. A Norwegian-flagged car hauler barely makes it under the 610 bridge, and its crew waves to us from 50 feet up as we pass.

In another typically Houston juxtaposition, this place where one would expect progress to wipe out all traces of the past contains more history than most of the city’s neighborhoods. We pass docks built in the 1920s, antique loading equipment and an oil refinery that first came on line more than 100 years ago. For those of us who didn’t take Texas history in school, probably the biggest surprise comes when the tour boat turns around in front of the squat marker that commemorates the spot where Sam Houston captured Santa Anna.

I’d be hard pressed to name another city where anyone can so easily head to the east end of town for a relaxing, free boat ride in an otherwise off-limits place. As an amateur sailor, I have an admitted tendency to romanticize sea travel.

But after stepping into Houston’s back room for a look at the ships and industries that keep our city humming, you might too.