A recent field survey at Ha Long and Bai Tu Long Bays in northern Quang Ninh province has added 23 new names to the list of local caves.
Nguyen Thi Thuy Duong, head of the Ha Long Bay management board, released the news, adding that 18 caves of the new discoveries are highly valued for their beauty and scientific features.
Further research on those caves will be conducted before being classified for conservation or tourism purposes, she said.
Ha Long Bay, which spans 1,553 square kilometres and houses 1,969 islands of various sizes, was twice recognised as a UNESCO World Heritage Site in 1994 and 2000.
Together with the neighbouring Bai Tu Long Bay, they form a tourism complex with thousands of islands, considered among the most valuable biological and geographical assets of the country and the world.