In the season premier of “Parts Unknown,” Obama and Bourdain chat over bun cha.

Credit: Parts Unknown/CNN

“The smell: that's the first thing that hits you,” Graham Greene wrote in his 1955 classic about Vietnam, “The Quiet American.” And it was with a focus on this that Anthony Bourdain kicked off the new season of “Parts Unknown.”

The powerful sense, linked strongly with memory, tied together every conversation Bourdain had in Hanoi and Halong Bay. He walked through heavy tropical downpours in Vietnam’s capital city, only barely joking, “Just another day in paradise.”

In the torrential rains, a crowd had formed and a limousine bearing the flags of Vietnam and the U.S. pulled up. President Barack Obama got out, carrying his own umbrella and waving to the cheering crowd.

Credit: Parts Unknown/CNN

When Bourdain greeted the president, he mentioned his perceptions of Hanoi’s intoxicating aromas.

“Yeah, there are certain spices you can smell in certain countries that you just don’t smell back home,” Obama agreed. “Now, there’s some smells that aren’t as appealing, as well, but that’s part of the mix.”

Among these less-pleasant smells is that of exhaust. Hanoi, a city of 8 million people, is also home to 4 million motorbikes. At the beginning of the episode, Bourdain pulled up on a motorbike and shared that there's no way to see the Vietnamese capital quite like from a bike among traffic.

Bourdain has talked at length about his fondness for the country ever since he first visited 15 years ago. In this episode, he focused on the changes Vietnam has undergone in that time. Tourism to the country is ever-growing and the standard of living is getting better. Much of the episode was filmed in Hanoi’s Old Quarter, a neighborhood which, according to Bourdain, doesn’t look so old anymore.

Years ago, many Vietnamese would wake up for morning Tai Chi in the park. Now, it’s Zumba. Bourdain met a friend and her Zumba instructor for noodles and a discussion of Hanoi’s changing demographics.

Credit: Parts Unknown/CNN

They went to a place called “Cussing Noodles,” named for its chef, a woman who won’t hesitate to tell customers to get out if they don’t know what they want. Bourdain knew exactly what he wanted: a bowl of noodles, drowning in a hearty broth with chiles and pork knuckles and snout.

He then met a friend for Bia Hoi, a draught beer ubiquitous in Hanoi.

“There’s only three to four percent alcohol in it,” his friend said, to which Bourdain replied, “So, we need to drink a lot?”

From there, it was onto Halong Bay. The UNESCO site has seen a big boom in tourism in recent years. Bourdain rented out an old French steamer ship and spent a night cruising around the bay, eating squid. “In general, it does not suck,” he said.

He got off the boat to eat with a floating fishing village. This sort of living arrangement used to be very common in the bay, but as tourism increased the government began offering incentives for the fishers to move ashore. Many of the fishers take the offer as living on land allows their children to go to school, Bourdain learned over lunch. He sat down cross-legged to eat freshly-caught fish, morning glory (a popular vegetable dish) and some noodle soup with them.

Back in Hanoi, Bourdain waited to meet the president. He took Obama for dinner at Bun Cha Houng Lien, a very “locals only” eatery in the Old Quarter. Bun Cha is an authentic neighborhood meal that not many tourists experience. It’s complex and requires some assembly.

“Get ready for the awesomeness,” Bourdain told Obama as he walked the president through the dish with small rice patties, vinegar sauce and cold rice noodles.

Over beer, Bourdain and Obama talked not only about Vietnam, but about being dads, the Chicago hot dog, and the acceptable age limit for using ketchup. Dinner and beer ended up costing Bourdain $6.

Bourdain sat down with a friend to talk about Vietnamese-American relations. In a country where half the population wasn’t alive during the influential global event, the American War seems like ancient history to many.

The American War Museum in Hanoi is often a must-see destination on tourists' lists. Bourdain asked his friend, a former tour guide, if one day she thought that the museum would not be as important, if it could be eliminated from the Hanoi itinerary.

“It’s good to remember so we don’t repeat the mistake,” she said. She talked about the former American war vets that she had met that came back to Vietnam as tourists, eager to understand the country and make meaningful connections with their former enemies. John McCain is one famous example.

The episode ended with scenes of Vietnam, Bourdain examining the spirit of understanding and forgiving your enemy and talking about the lingering smells of the country—and the powerful memories associated with those aromas.

The motorbike exhaust, the fish sauce and the crumpled body of a B-52 are all equally important in understanding Bourdain’s sensory Vietnam.

Cailey Rizzo writes about travel, art and culture and is the founding editor of The Local Dive. You can follow her on Instagram and Twitter @misscaileyanne.