A man who was paid to travel around the world for a year swears by one piece of clothing for traveling between sub-zero temperatures and tropical climates

• Sebastian Modak brought just one carry-on and one checked bag with him on his trip around the world in 2019 as the New York Times' 52 Places traveler.
• Modak visited 52 destinations and a range of climates, from sunny Puerto Rico to frozen Lake Superior.
• During the 17th annual New York Times Travel Show, which took place this past weekend at the Javits Center in New York City, Modak sat down with Wirecutter staff to discuss how he packed for his trip and what items were the most reliable.
• When it comes to clothing, Modak swears by merino wool.
• Visit Business Insider's homepage for more stories.

In 2019, Sebastian Modak flew 119,772 miles, took 88 one-way flights, and visited 52 destinations around the world for The New York Times - all with just one carry-on and one checked bag.

Modak traveled to both incredibly cold climates, such as Canada in the dead of winter to see the Ontario Ice Caves, and tropical climates, like Puerto Rico.

This past weekend at the 17th annual New York Times Travel Show, the largest trade and consumer travel show in North America, Modak sat down with Wirecutter senior staff editor Ria Misra and writer Kit Dillon to discuss how he packed for the trip of a lifetime and navigated vastly different environments.

When it came to clothing, Modak swore by shirts made of merino wool to keep him both warm and cool - but how exactly does that work?

Merino wool "might be magic," Modak wrote in a Reddit thread created by the New York Times halfway through his trip.

Magic isn't far from the truth. Merino wool fibers change form depending on the temperature outside. "When it's cold outside, the natural crimps and bends in its fibers trap air, insulating you. When it's warm outside, it transports sweat quickly away from the skin, helping to keep you cool and dry," popular sock brand Smartwool explains on its website.

"The natural fibers of wool are actually great for regulating temperature and providing UV protection," Tyler Lauletta wrote in his Insider Picks review of a fitness clothing line by QOR. "They're also antimicrobial, so they can help with reducing odor."

Sheared from merino sheep, the sweat-wicking fibers are thinner and softer than the wool most winter wear is made from. Smartwool's choice words are "crazy comfortable."

What's more, merino wool is notoriously wrinkle-resistant. Packsmith, a blog that shares packing tips and tricks from seasoned travelers, awards the fabric a 10 out of 10 on its wrinkle-resistant scale.

Socks and fitness wear are frequently made with merino wool. Recently, shoe companies have taken note as well. In 2016, trendy footwear brand Allbirds cast merino wool into the spotlight when it debuted its wool runner line. Last year, women's footwear brand Rothy's followed suit with the launch of its Merino Collection.

Business Insider's first international correspondent Harrison Jacobs, who traveled the world over the course of a year, similarly swears by merino wool. He listed Smartwool's "Darn Tough" socks among his top five essential clothing picks for extended travel.

The key to packing for any long trip, Jacobs and his travel partner noted, is purchasing clothing that can serve multiple purposes. "The key, we found, was picking items that serve dual purposes, like hiking boots that look good on a dance floor or a short-sleeve turtleneck that looks as good in the boardroom as out on the town," he said.