My girlfriends all want to know: How many pairs of underwear am I taking on our around-the-world journey?

In my whole life, including all the slumber parties I attended as a girl and lingerie-themed wedding showers over the years, I have never talked so much about panties as I have in the last month.

In making a packing list for the trip, I began to understand the obsession with underwear. We’ve got to pack light because we intend to carry our belongings onto the plane, so every item we can delete from the packing list is a bonus.

Plus, lugging big bundles of clothes, cameras, computers, and books up arduous hillside trails to get to the family hostels we’ve booked won’t be easy. (In my imagination, the accommodations are always up arduous hillside trails…)

All along, I hadn’t worried about underwear heavying up the load. A few handfuls wouldn’t take up that much room, right? And what could be more important than a clean foundation?

But seeing everything actually stacked up and laid out for packing is alarming. Even the tiny mountain of cotton briefs can’t be entirely justified. For help, I turned to what has become our travel guru — the BootsnAll website.

On the BootsnAll discussion boards expert travelers debate underwear strategy in detail: I read about favorite brands, the pros and cons of cotton, and whether to go with thongs (that’s a no) or a modest boxer style to make “quick, public changes of clothes go more smoothly.” (Yikes!)

I have learned that, as with technological leaps in electronics, there has been great progress in underwear technology. We are advised to avoid, for this kind of journey, our dungarees and cotton clothing that could take hours and hours to dry on makeshift laundry racks and clotheslines.

Instead, experienced travelers buy cleverly engineered cloth that wicks moisture (essential for those hot days), offers sun protection (not as critical in undergarments to be sure), has odor control (a definite plus), and is made from recycled fibers (gotta be green!).

The other day my friend Laura gave me the perfect gift, a product that makes the following pitch:

“Seasoned travelers save room by packing just one or two pairs of our underwear. They wash one at night and wear the other. Great fit and comfort in the most important layer you will put on.”

Call me old-fashioned: I’m opting for two!