(Image: AAP/James Gourley)

Among the many, many other things it is, COVID-19 is the most substantial threat to the viability of global tourism in at least 100 years.

"At this stage, any forecasts about a travel industry recovery are better described as guesses," Rod Cuthbert, founder and former CEO of travel-booking service Viator, told Crikey. "There's no science underpinning them, and nothing in our history serves well as a guide."

Everyone Crikey spoke to offered that caveat.