Summer 2021 was, for some, supposed to be a big rebound for travel.The U.S. hotel industry in June recorded its highest monthly occupancy and revenue per available room since October 2019. Domestic air travel demand had reached pre-pandemic levels, with the Transportation Security Administration regularly screening over 2 million passengers a day. And popular destinations like Canada and the European Union reopened to vaccinated American travelers.But there are signals around the globe that the delta coronavirus variant is negatively impacting travel.While 60% of Americans over 12 are fully vaccinated, large parts of the world still wait for vaccines. Now, one popular Caribbean destination has closed for tourism, while others introduce restrictions. Here’s what you need to know.For more TPG travel news and tips delivered each morning to your inbox, sign up for our free daily newsletter!The latestMartinique – Saint-Pierre. Photo by Luc Olivier / Getty ImagesFrench overseas territory Martinique went into a lockdown on Aug. 10, expected to last at least three weeks. During the lockdown, beaches, cultural and leisure sites, and non-essential businesses are closed. Residents can only travel within a kilometer of their homes, and a curfew between 7 p.m. and 5 a.m. has been put in place.But tourists have been asked to leave, a sign that some travel may be regressing to the early days of the pandemic. In announcing the restrictions, Stanislas Cazelles, the prefect for Martinique, asked “all vulnerable tourists to leave the territory.”“We will be entering a second phase of lockdown,” Cazelles said.The U.S. Centers for Disease Control and Prevention (CDC) lists Martinique in its highest level 4 designation and advises against all travel to the island.Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.This ranking is determined based on the number of cumulative new cases per 100,000 people over the past 28 days and new case trajectory (if the new cases rates increase, decrease or remain stable). Level 4 notices indicate an area with at least 100 new cases per 100,000 people.Martinique has reported nearly 28,000 positive cases of the coronavirus – over 15,000 of them reported in the last 28 days – and 184 fatalities, according to Johns Hopkins University’s COVID-19 tracker. Just under 87,000 doses of the COVID-19 vaccine have been administered on the island.Other countries that have put restrictions in placeFrench Polynesia (Photo by Summer Hull/The Points Guy)Other French overseas territories popular with tourists include Guadeloupe, French Polynesia, Saint Martin and Reunion Island. Many have implemented measures to slow the spread of COVID-19.Guadeloupe, for instance, is under lockdown from 9 p.m. to 5 a.m., which went into effect on Aug. 4. Bars, gyms and swimming pools are closed, while restaurants are open for midday service, according to EuroNews. The head of the island’s health agency called the COVID-19 situation “catastrophic,” saying the island exceeded 3,000 cases per week. In the Indian Ocean, Reunion Island is also under a partial lockdown, while French Polynesia is under an overnight curfew.Other places – some of which had dropped restrictions earlier this year – have imposed regulations to slow the spread of the virus.Hawaii announced on Aug. 10 that restaurant and bar capacity would be reduced to 50% due to an increase in positive cases. Social gatherings are now limited to no more than 10 people indoors and no more than 25 outdoors. “High-risk” indoor activities such as bars, restaurants, gyms and social establishments are capped at 50%. Hawaii’s governor said the new measures resulted from the highly transmissible delta variant and said the situation “requires immediate and serious attention.”Elsewhere, New York City will require proof of coronavirus vaccination to dine indoors at restaurants and participate in other indoor activities. The policy is expected to begin this month and is an attempt to encourage more people to get vaccinated.