The resort has an infinity pool lying at 900 meters (3,000 feet) above sea level and surrounded by green mountain ranges, Singapore-based online travel booking platform Agoda said.

Situated atop a hill, the pool allows eye level contact with the Hoang Lien Son mountain range and stunning terraced fields. To add luxury to this beauty, the pool has a power-saving heating system that provides the warmth you need in chilly conditions.

"Billed as a holistic wellness destination, the northern Vietnamese destination-resort has become a model for the nation in terms of both community support and sustainable tourism, employing local villagers and reducing single-use plastic," Agoda wrote.

Opened in 2005, the five-star resort offers 41 bungalows built with white granite that resemble ethnic minority stilt homes. All furniture is made from natural materials like wood, bamboo and rattan.

Just 15 kilometers from downtown Sa Pa, Topas Ecolodge has been named a top eco-friendly resort by National Geographic.

The six other names voted by Agoda readers were Keemala Resort & Spa in Thailand, Rosewood Hong Kong, Marina Bay Sands in Singapore, Grace Santorini Hotel in Greece, Four Seasons Hotel Istanbul in Turkey and Lefay Resort & Spa Lago Di Garda in Italy.