People coming to Halong Bay often hear about famous caves such as Sung Sot (Amazing cave), Luon (Tunnel cave), and Thien Cung (Heaven Palace cave) which are very beautiful but quite crowded with tourists in recent times. But if you go further, to a more quiet area, (for example, just 2 kilometers from the Amazing cave), you will find two extremely special caves where limestone mountains meet the sea to create a unique combination of nature: Bright and Dark Caves. This area lies on the border of Halong Bay, Bai Tu Long Bay, and Lan Ha Bay, near Cat Ba National Park. Formed by an enclosed group of islets, these caves connect with the sea via a 4-meter-wide, 100-meter-long, and 3-meter-high mouth.
Although not as famous as Halong Bay , and with perhaps fewer specially shaped rock formation, Lan Ha Bay with its Bright and Dark caves well earns its place as an inescapable piece of the World Heritage site which it is part of, and we think it is certainly one of the best places for kayaking, swimming or photography. Cruising to Bright Cave, you will see an angled passageway opening the cave at water level. Inside the lovely passage is a serene round lake surrounded by lush trees and precipitous stone cliffs, reminiscent of a stadium surrounded by a high platform.
Going around the lake, you might imagine being in a colorful garden with the Benjamin fig trees and various sweet-scented orchids spreading their blooms, close enough to touch. Not being surrounded by islets like Bright Cave, Dark Cave is long and dark, like a tunnel. Because it is very dark inside (hence its name) anyone going through it needs a torch to light the way. Unlike Bright Cave which is always available for visiting, Dark Cave can be engulfed by the tide when the moon is high, so it is not usually listed in cruise itineraries