A “deployable” barrier is shown in use at the MBTA’s Aquarium subway station. City of Boston photo

On any given day, you’re likely to bump into all manner of walking tours in Downtown Boston, most of them populated by tourists following in step to a Freedom Trail guide dressed in his or her finest colonial garb.

But this Friday afternoon will feature a new cluster of pedestrians traipsing around Faneuil Hall and environs. The Wu administration has dubbed it “Deployable Day” and it’s meant to be an immersive experience in the city’s preparations to guard against rising sea levels and the resultant flooding that is already a fact-of-life for waterfront neighborhoods.

“Learn about the City’s flood protection measures, ways to stay safe during a flood, and whether a deployable is right for you,” reads a city statement promoting the tour, which will be led by Brian Swett, the city’s newly installed Chief Climate Officer, and Chris Osgood, director of Climate Resilience. (The tour starts at noon at the Congress Street entrance to City Hall.)

What’s a “deployable?”

As the photo here shows, it’s a temporary barrier that can be installed at key locations – MBTA station entrances, building lobbies, etc. – to mitigate flooding events. They are typically metal walls that can be folded into place before a tidal event or storm to seal off infrastructure that might otherwise be inundated.

The city is calling Friday’s “first annual” event a citywide training exercise, although it’s mainly focused around the downtown area. But these contraptions are almost certainly going to be in use in Dorchester, South Boston, and other coastal communities in the coming years, according to city officials.

Unlike the permanent natural berms that will be landscaped along the Morrissey Boulevard corridor, for example, the deployables can be stored out of sight when they’re not needed. And they are considered superior to sandbags because they can easily be re-used and do a better job in protecting assets like buildings and equipment from water damage.

Who should go to “Deployable Day?” If you live in a flood-prone zone – or manage or own a property there – it’s a good opportunity to get acquainted with the technology and vendors in the industry, some of whom will be on hand to offer live demonstrations during the (cue the Gilligan’s Island theme song) three-hour tour.

Get more details on the city website: boston.gov/deployables day.

– Bill Forry