By the time we reach Ti Top beach, the sun is low. Though small, the beach is pristine, while the water in the bay is calm and inviting. I float on my back, watching thin pink clouds drift past as the sun sinks slowly behind an immense chain of islands.

Refreshed by the swim, I climb 300stairs to lookout point, which offers a stunning view of the bay and the setting sun. Half of the sky burn a vibrant orange, while the water has turned a shimmering turquoise, cut by currents, which shine with all the colors of the rainbow. When the sky has faded to deep violet I return to the junk, enticed by the lights and the smell of dinner.

The captain now turns the Huong Hai towards Bai Tu Long Bay and hoists the sails. After a day of swimming and exploring, everyone is hungry. We feast on fresh seafood, trying to restrain ourselves, as the captain tells us that other late night meal will be prepared from what we catch later tonight.

After the dinner, the junk anchors somewhere near Cat Ba Hai Phong. At about 9p.m., we don life jackets and board small bamboo rowboats, and the dim outlines of islands. The rowers work quietly and smoothly, moving the boats as if along a path cleared for them by the men holding the flashlights.

The water is so clear that the beam of the flashlights seem to reach the seabed. We hold small nets, posed and waiting. A school of small fish appears. "They are too small to catch" says the guide. Now some larger fish and eels appear, attracted by the bright lights. With a flick of the net, I catch a squirming fish. We all cheer.

Soon after, we glide to wards Doi (Bat) Cave. Keeping our heads low to avoid the stalactites, we are so daxxled by the flashlights that it takes some moments for someone to see the small red patches on the rocks below. "Sea crabs" someone yells. "Grab them" I target a clever crab, which scurries into a crevice and escapes. Other crabs are not so lucky, and find themselves tangled in our nets.

After half an hour we are old pros, able to spot the crabs at a distance. We are also more skillful with the nets, so less crabs escape. Deep in the cave, it is strangely silent; the only sounds are the gentle tapping of the waves against our boats and the whirring of bats' wings. The cave smells of salt water and bats.

Unwilling to break this deep silence, we all sit quietly, lost in thought. Cocooned in quiet, the problems of the Outside world seem far away. One passenger is so pensive that his net droops into the water, causing by the surface to crackle with phosphorescent sparks. Inspired by this discovery, one young man peels off his jeans and leaps overboard, his body sparkling like a flaming torch. "During moonless nights", says one of the guides, "phosphorescence is much stronger". It is midnight when we pull up to the junk. The crew cooks up our catch fish, squid, crabs and shrimp. We grab some bottle of beer and white wine and climb onto the deck to eat. After ending the meal with some fish soup. I retire to my cabin. Some other passengers choose to sleep o the deck, under the stars.

In the soft light of early morning, the sea glows blue, inviting us to take one last swim. Then it is time to turn back towards Ha Long Bay. As we are cruising back, it starts to rain. The bay in suddenly transformed, the island blurred like a water color. By the time we reach the wharf at noon the shower has passed.

It is hard to believe the we spent just 24 hours aboard the Huong Hai. In a singly day on Ha Long Bay, we saw and experienced so much. While we must now return to Hanoi, we all take some of the bay's magic with us.