Seawater cascades over an ancient coral reef, Hang Rai, Vietnam

© Thang Tat Nguyen/Getty Image

Vinh Hy Bay, Vietnam

Welcome to Hang Rai, a blend of ancient rock formations and vibrant coral reefs! Also called Rai Cave, this cavern is part of the Vinh Hy Bay—enclosed by Nui Chua National Park—in the South Central Coast region of Vietnam. The area's natural coral reefs are surrounded by rock formations, that are carefully stacked upon each other to form a group of caves. One origin of the name 'Hang Rai' or 'Rai Cave' comes from otters (rai) that were occasionally seen seeking shelter in the cave. Another explanation is attributed to the abundance of rai trees in the area, whose oil was used to waterproof boats. The landscape has an awe-inspiring sight both under and above water: colourful corals for deep divers and a scenic sunset for those who like camping in the sea breeze.