It's 6 months since Australia and New Zealand first floated the concept of Travel Bubbles. Ever since, it has dominated travel talk as a potential way to safely reopen borders between two countries without requiring a quarantine. But the 2020 travel realities (and the coronavirus itself) have made bilateral bubbles extremely difficult to negotiate, agree and implement. This week, Gary and Hannah discuss the different definitions of air travel bubbles, corridors, fast tracks and green lanes. They also assess three high-profile travel bubbles - Hong Kong-Singapore, Australia-New Zealand and India-Maldives - which illustrate the political, geographical, public health and operational challenges that stand in the way of more agreements.