During the Covid-19 pandemic, perhaps no other industry has been harder hit than the global travel and tourism sector with planes grounded, resorts closed and care-free vacations a distant memory for most of us.

Some countries in Europe — Greece, Spain and Portugal, for example — rely on tourism to boost economic growth with the prosperity of thousands of businesses, livelihoods and communities tied to the success or failure of the season.

As Covid vaccinations were rolled out across the region since late 2020 there were high hopes that Europe could look forward to a rebound in summer tourism this year.

Instead, the season is looking highly uncertain as the delta variant surges in Europe, prompting a plethora of varying rules and restrictions, traffic-light systems designating country risk profiles as well as possible quarantines and vaccine entry requirements.

Travel within Europe these days is certainly not for the faint-hearted, in more ways than one. The Covid infection rate has surged across the region as the highly infectious delta variant has swept the globe.

As with the previous alpha variant (which delta has now usurped) the U.K. was something of a harbinger of doom when it came to what the rest of Europe could expect. Britain saw a further Covid wave at the start of the year caused by the alpha variant and is now seeing another wave with delta.

Despite efforts in the continent to hold back the variant, the inevitable spread has taken place with the strain now accounting for the majority of new infections from country to country.

The Netherlands and Spain have seen big surges in cases, largely attributed to the night time sector after both countries reopened their nightclubs in late June, only to reverse course two weeks later. Meanwhile, France declared it was entering a fourth wave of the pandemic earlier this week, with government spokesman Gabriel Attal sounding the alarm:

“We have entered a fourth wave. The dynamics of the epidemic are extremely strong. We see a faster wave, and a sharper rise than all the previous ones … the incidence rate continues to explode … A rise so big, so sudden, we haven’t seen that since the beginning of the pandemic,” Attal said on Monday.

Tourism and airline stocks took a beating at the start of the week when global markets plunged sharply on renewed fears for the global recovery. EasyJet and Ryanair, well-known low-cost airlines in Europe, were among the stocks seeing pronounced declines. Shares of easyJet, for example, were trading at 842.20 pence on Friday but plunged to 758.20p by Monday early afternoon.

Easyjet’s CEO Johan Lundgren told CNBC on Tuesday that the travel sector was facing an “extraordinarily challenging” situation, but that vaccination programs in Europe were the key to reopening. Data shows two doses of the Pfizer-BioNTech or AstraZeneca-Oxford University are effective against the delta variant and lower the risk of hospitalization and death.

“We always knew that [the recovery] was not going to be a straight line … But we are seeing that restrictions are being unwound. But it’s absolutely true that when you do open up societies and communities, there is an increase also in infections. The question is to make sure the vaccinations are breaking the link between [infection and] severe hospitalization and death, and fortunately it looks to be that way,” Lundgren told CNBC’s “Squawk Box Europe.”

Anyone making last-minute plans for a European vacation this year should brace themselves for an often confusing, complex and rather stressful experience — and that’s before you’ve even stepped off the plane.

Take going to Greece from the U.K. — a vacation that 3.4 million Brits did in 2019, official statistics show — as a general example of the complexities of going on vacation in these troubled times:

Greece is allowing visitors from the U.K. if they can provide proof of a negative Covid-19 PCR test, undertaken within the 72-hour period before arrival into the country or proof of a negative rapid antigen test undertaken by an authorized lab within the 48-hour period before the scheduled flight; or proof of two doses of a Covid vaccine completed at least 14 days before travel.

Before you even get to Greece, however, you have to fill in a Passenger Locator Form no later than 11:59 p.m. (local time) of the day before arriving stating your vaccination status, vacation address and next of kin. Then before returning to the U.K., holiday makers have to do a PCR test and fill out another passenger locator form and then within two days of after arriving back in the U.K. do a further PCR test or quarantine for 10 days.

All that, and Greece is actually one of the easier places to go on vacation this year.

Like its fellow European countries, Greece has not escaped the somewhat inevitable rise in Covid cases as the economy (particularly the island night time economy) has opened up. Still, the daily number of cases appears small compared to, say, France or the U.K. On Wednesday, Greece reported 2,972 new cases, 19 of which were located after checks at the country’s borders.

Wolfango Piccoli, co-president of risk consultancy Teneo Intelligence, noted on Wednesday that the resurgence of Covid-19 in Greece “poses new challenges, especially with regard to another meager tourism season and the economic consequences that will follow,” circumstances that put pressure on Prime Minister Kyriakos Mitsotakis.

“Mitsotakis had been hoping to leave the pandemic behind this summer as his center-right government reached the midway point of its four-year term in office. He was aiming to oversee an improvement in tourism receipts, the launch of Greece’s recovery plan and a return to growth. However, Covid-19 numbers have risen significantly in recent weeks and the vital tourism sector is already pushing for more state support in the autumn amid fears of more disappointing visitor numbers this year,” Piccoli noted.

As the Delta variant is gradually becoming more dominant, Piccoli noted that Greece faces a conundrum as “the number of daily vaccinations has slowed this month to below 100,000 despite the government offering Greeks aged 18-25 a 150-euro ($177) incentive to get vaccinated.”

So far, he said, only around 120,000 out of an estimated 980,000 Greeks in this age group have been vaccinated.

Vaccination levels in the general population have reached almost 52% for at least one dose of the vaccine and nearly 44% for complete vaccination, Piccoli noted, adding that “the recent slower uptake has raised doubts about whether the government can achieve its target of vaccinating 70-75% of the adult population by the end of the summer.”