As the white, 95-foot Sam Houston tour boat pulls off to make its way through the Houston ship channel, dozens of elementary school students sit in the cool, air-conditioned cabin to hear the safety rules: no running, no playing or leaning over the rails inside or outside.

The boat chugs along at around 10 miles an hour. Over the loudspeaker, the automated tour begins. A smooth, southern voice explains that we are 52 miles from the Gulf of Mexico and the open sea. Unlike the ocean-bound vessels docked along this industrial waterway, the Sam Houston is not making it all the way down the entire 52 miles down the channel.

While you may be hard-pressed to find the brown-watered Houston Ship Channel on anybody’s bucket list as other iconic works of infrastructure sometimes are — think the Golden Gate Bridge or the Eiffel Tower — this 110-year-old dredging work is critical to U.S. oil and gas exports and is home to refineries and storage facilities for major companies like Valero, LyondellBasell and ITC. Without the channel — built not long after the discovery of oil in the area — Houston would never have become Houston.

And what it may lack in natural beauty the boat tour makes up in price (it’s free, refreshments included) and comfort (large, cushioned seats and AC). Locals, community groups, school children and tourists from around the world have taken thousands of voyages on the Sam Houston since it began operations in 1958.

Aboard the Sam Houston, Port Houston public relations director Lisa Ashley-Daniels steps outside onto the deck as the boat passes by aging warehouses and city docks. 

“We’re just now disembarking and getting on the way on the upper part of the Houston Ship Channel where the bayou tributaries come together where the channel was actually dredged from there, seven miles shy of downtown Houston, to Galveston Bay,” she said.  

Ashley-Daniels said that the ship channel was built soon after the 1900 Galveston hurricane, which was the deadliest natural disaster in U.S. history and was a warning to build trade further inland. 

The building of the ship channel also followed the Spindletop oil discovery about 80 miles east of Houston, paving the way for the city to become an energy capital. Today, roughly 70% of what is imported and exported through the Houston Ship Channel is petroleum products, according to S&P Global. 

“We were able to draw business,” she said. “And at that time in 1914, that was when we dredged it. That was also the same time the Panama Canal was created.”

Houston Ship Channel grew into a vital trade route. Today, the Port of Houston is the No. 1 port in the U.S. by tonnage, according to US TradeNumbers analysis of government data.

Upstairs, Ashley-Williams introduced the two captains of the Sam Houston tour boat, Genaro Ambriz and Greg Penton.

Penton, who was steering, used the radio to speak with an approaching barge. 

“You see this barge coming around the corner? I just called for passing agreement,” he said. The barge looks like a flat floating rectangle with garbage cans and is part of a new dredging project to widen and deepen the Houston Ship Channel.

“They’re using large … clam buckets, and they’re grabbing mud from bottom and they’re putting it into these barges,” he said. “We keep waiting for it to bring out a car or something.”

It’s a $1.56 billion infrastructure improvement project funded by the federal government and Port Houston. 

Environmental concerns have been raised recently around the dredging project, as cancer-causing chemicals were recently found in sediment brought to land from the expansion project.

We voyaged further through Houston’s industrial underbelly and Captain Genaro Ambriz pointed to a cement plant, a petroleum product storage facility, refineries. We passed several very large ships, including one called the Seaways Hercules.

“You see all these pipelines that run across the top. Whenever you see a ship like that there, it’s called a tanker,” he said. Tankers are filled with crude oil and other petroleum products.

Sometimes, the foreign workers on these massive tankers wave to the tour boat. Penton said he’ll look to see what country they’re from and wonder about their lives, where they’ve come from and how they got into the maritime business.

“They’ll work six months straight on that ship without ever getting off that ship,” he said.  

After 90 minutes or so, as the tour wraps up, incoming third grader Penelope Basaldua said she had a nice time on the boat with her classmates.

“I saw water. I saw trash inside the water and ships around us,” she said. 

She got a free, air-conditioned yacht ride through one of the most important ports in the United States — it’s been a little adventure on a hot summer day.