> Ba Ham Cave 

Informally called the “Indochine Cave” ever since the film starring Catherine Deneuve was shot here, this short grotto leads to a hollowed island lagoon with steep walls of jungle surrounding shallow salty waters. On budget trips to Cat Ba Island, boats stop at the entrance and small shuttle boats will take you to the cave through low openings. The cost is 20,000 VND ($1.35) for the short ride, but the proceeds allegedly go to help the small floating school in the nearby floating village (you pass the school on the way).

> Dau Go Cave (The Cave of Stakes) 

Reputed resting place of the long stakes that Tran Hung Dao used to sink the Chinese fleet that came to attack Halong and Haiphong, Do Go is a massive cave with three chambers, not far from Thien Cung.

> Drum and Virgin Cave 

Adjoining the most popular place for overnights in Halong Bay, this stunning and quiet nook in the bay is a place where you might be able to interact with some local fisherman if you can get out on the water in a kayak. The caves are on opposite sides of the calm bay, and each is but a shallow area. Some tours even set up fully catered meals with banquet tables in the caves.

> Surprise Cave 

What’s the surprise? The French arrived and said, “Mon dieu! Why, it is a cave!” Discovered in 1901, this very large grotto was used by Viet Cong as a hideout during the war with the United States. A short, steep climb up paved steps leads you to three chambers, the last being the largest. In 1999 the Chinese cooperated to install lights and a safe pathway through the cave. A tour of the cave usually involves a guide leading you on an interpretive stalagmite hunt. Guides like to point out a large phallic formation glowing under a bright red spotlight — Freudian interpretations of the rock formations abound. Also look for the tiger, dragon, and penguin formations, as well as unique “melon ball” stalactites. Toward the top of the caves, you’ll find viewing platforms overlooking the sprawling bay, with its myriad junks, far below.

> Emeraude

For a unique high-end experience, book passage aboard the Emeraude — a copy of a French steamer that once plied these waters in the early 20th century. Certainly the largest boat at 55m (180 ft.), the elegant Emeraude has 38 cabins, a fine-dining outlet, and plenty of room to stretch your legs. The luxury trip comes with a price tag, of course, but the 2-day, 1-night cruise is well worth it.Leaving Hanoi at 8am, you’ll check in at the private Emeraude pier and be shuttled to the boat. Before checking in to your cabin, you’ll enjoy welcome drinks and a quick orientation. Compact, as ship cabins always are, onboard rooms are decked out in hardwood, with nice fixtures like air-conditioning, a private reading lamp, slippers for shuffling about the decks, and a tidy, compact bathroom area with toilet, shower, and a separate room for a small sink stand. Everything onboard is retro, which means pleasing hardwood, brass, and fine linens. The oversize wicker chairs on the top deck are cozy, and you’ll find shaded areas as well as sun-worshipping space. A casual, friendly atmosphere pervades, especially when the corks start popping.

Dining onboard is a delicious buffet, and most guests find themselves sharing a meal with new friends. Lunch on day 1 is followed by a stop at the Surprise Cave, then an afternoon of cruising and great views of the islands. The boat docks in a quiet harbor and guests have an opportunity to, on their own or with a guide, explore nearby Trinh Nu and Hang Trong, the Virgin Cave and the Cave of the Winds, or take a dip in the bay. The back of the boat is low in the water and there is a sturdy ladder making it easy to get on and off (the adventurous will join the crew for dives off the upper decks). Dinner is a sumptuous affair of fine local cuisine (heavy on seafood) and good Western options. Enjoy drinks on the upper deck as you watch the moonlight glisten off the bay.

Day 2 starts with tai chi classes on the sun deck as a brilliant sunrise paints its colors on the arching canvas of high limestone peaks jutting from the glassy waters. Blissful. After your exercise, tuck in to a hearty Western-style breakfast. The boat returns to the dock by 9:30am, and a direct transfer finds you back in Hanoi by lunchtime. The trip is quite memorable, and a ride on this retro ship, outfitted to the nines, is unique to Halong Bay. The price for the overnight cruise is $290 for a luxury cabin for two and $490 for the one-suite room, but discounts for larger groups are available. Transfer from Hanoi costs $100 for a four-seat vehicle. Check the website at www.emeraude-cruises.com or call the offices at the Press Club in Hanoi (tel. 04/934-0888; fax 04/934-0899).

> Thien Cung Grotto (Heavenly Cave) 

One of the most popular caves for day trips, a visit to Thien Cung starts from the crowded dock area where wooden walkways lead to steep stairs going up to the mouth of the cave — just a short walk. The interior is a cavernous space, with hokey circus lighting, lots of big rock formations, and the usual interpretive names. This is considered the Cave of the Dragon, where the dragon who created Halong sought refuge, and guides are quick to point out one elaborate stalactite that looks like a dragon (or maybe a hoagie, depending on your interpretation). There’s a legend surrounding the cave about a young girl who, in order to end years of oppressive drought, married the presiding dragon in the cave, and their wedding was attended by all in the animal kingdom. Brave girl. It is a “dead cave” in that, unlike many limestone caves, it is no longer dripping water and growing formations of additional deposits or creating new fissures and caves. Lit like a Vegas casino, this is the first cave most visitors reach on the way to Cat Ba Island.