Until recently, even amid years of Brexit negotiations, travel not just in continental Europe but between Europe and the U.K. was nearly seamless: countless bargain-basement flights left airports across the country daily, and Paris and London were just a relaxed, two-hour train journey apart.

That ease has been ended by the COVID-19 pandemic, but it hasn’t stopped Britons from going on holiday this summer. Instead, it’s added a new level of chance and risk to the proceedings, with countries rapidly being added to or taken off the country’s 14-day quarantine list with less than 48 hours notice—infuriating travel bookers, confusing tourists, and provoking scrambles to cross the English Channel.

“Only travel if you are content to unexpectedly 14-day quarantine if required (I speak from experience!)”, transport minister Grant Shapps warned on Twitter. Shapps was forced to return early from a family holiday in Spain in July after the country was placed on the quarantine list.

This week, Croatia, Austria and Trinidad & Tobago were added to the quarantine list, giving tourists who wish to avoid self-isolation just 36 hours to get back to the country before the rules enter effect from Saturday morning at 4 a.m. On the other hand, Portugal—a beloved travel destination—was taken off the quarantine list, raising hopes for a late-summer holiday rush.

Croatia is estimated to be currently host to up to 20,000 British tourists, according to travel expert Paul Charles, who is the CEO of the travel consultancy The PC Agency.

That switch followed similar high-drama announcements for travelers arriving from France, last week, and previously Spain, provoking mad dashes to get back to the U.K.

The rules have drawn outrage from travel bookers and travel companies, who are wrestling with cancellations and extreme fluctuations in bookings. When the U.K.’s quarantine rules went into effect in June, they drew vast complaints from the sector that they had called for quarantine rules ahead of or in the midst of the country’s two-month lockdown—when no such rules were in place—and that applying them in June, by which time the U.K. had the highest death toll in Europe, made no sense.

Since then, a cottage tracking service has sprung up, with travel experts like Charles posting regular updates on infection rates among popular holiday destinations to warn of future changes, rumors flying of where to go, and when, and others tracking flight prices once quarantine restrictions go into place.

Some of the calls to moderate the quarantines have included calls for “regional” restrictions—including from the Croatian Ambassador, who noted that cases were rising in the capital, not in the tourist hotspots—and testing services at the airport. Both have been dismissed by the U.K. government: in the first case, transport minister Shapps said other countries didn’t have the detail or level of testing found in the U.K., making it difficult to assess their regional infection rates; in the case of airports, he said that it was “a bit more complicated” than often suggested, and would require a second test days later.

Chaos has reigned in other ways, too. Scotland, for example, has put Switzerland on the quarantine list—even as the country remains on the safe list for England. And there are other twists, in keeping with the U.K.’s byzantine rule-setting on everything from seeing parents during a lockdown (one at a time), to going to the pub (don’t sing, please.)

This week, fact checking service Full Fact confirmed with the U.K. government that a returned traveller may leave quarantine within the two week period—to go to another country. Whether they then need to complete a quarantine at all when they return to the U.K. depends on where they went, and for how long.

However, there was a lingering question hanging over the quarantine list: whether quarantines were actually being enforced. On Friday, the transport minister Grant Shapps said on BBC Breakfast he did not know how many people had been fined under quarantine rules, as travelers said there were no checks to see where they had arrived from, or if they quarantined at all.