Vietnam joined Morocco, Mauritius, India and Pakistan in the bottom five of the ranking compiled by British market research firm Euromonitor.

The country lagged far behind all its Southeast Asian neighbors like Laos (51), Myanmar (59), Cambodia (74), Thailand (76) and Malaysia (85). Indonesia took up the 92nd spot, followed by Singapore and the Philippines.

The index, which ranked 99 countries and territories around the world, analyzed seven aspects of sustainable tourism, including environmental, social and economic sustainability, country risk as well as sustainable tourism demand, transport and lodging.

Globally, Sweden has been ranked the most sustainable destination for travel, followed by Finland and Austria. Rounding out the top five are Estonia and Norway.

"Sustainable travel has raced to the top of the tourism agenda in recent years. However, only 55 percent of travel businesses implemented some form of sustainability strategy," Euromonitor said.

The research firm predicted there would be growing awareness among consumers, businesses and governments to prioritize the planet alongside people and profit when global tourism begins again following travel restrictions across the world.

Some popular tourist destinations in Vietnam have been eyeing sustainable tourism development.

For instance, Hoi An in central Vietnam is restricting the use of single-use plastic items and plastic bags as it looks to boost sustainable travel growth.

The ancient town, a UNESCO world heritage site, has been a pioneer in the country since 2004 for ensuring pedestrian-friendly streets. Motorbikes and cars are banned from the town center for large parts of the day – from 9 a.m. to 11 a.m. and from 3 p.m. to 9:30 p.m.

Cu Lao Cham, or Cham Islands, a UNESCO-recognized world biosphere reserve near Hoi An in Quang Nam Province, abandoned plastic bags and started a campaign to clean up the environment back in 2009.

Prime Minister Nguyen Xuan Phuc in 2019 said that Vietnam should strive for zero disposable plastic use in urban stores, markets and supermarkets by 2021 and for no plastic products to be used across the entire country by 2025.

The country has been ranked the fourth biggest polluter of oceans in the world by U.S.-based non-profit environmental organization Ocean Conservancy.