Diving Halong Bay with Halong Tours: When & Where to Go

Top Diving & Snorkeling Spots in Halong Bay

Cong Do Island – The Coral Lagoon of Bai Tu Long

• Location: Bai Tu Long Bay, 25 km southeast of Bai Chay Port, Halong City, Quang Ninh Province

Renowned for its coral reef stretching 7 kilometers long, Cong Do Island is a tranquil retreat for beginner and intermediate divers. Protected in the bay of Bai Tu Long Bay, the lagoon area of Cong Do is inhabited by a thriving community of red coral, sea urchins, giant clams, squids, and shrimp.

This site is best accessed via a private diving boat or as part of a Halong Bay diving cruise operated by eco-certified agencies like Impress Travel. What makes it extra special? You’ll find rare red coral formations, something few islands in Vietnam can offer. Water visibility here ranges from 8 to 12 meters during peak season.

Cong Do Island (Source: vietnamscubadiving)

Lan Ha Bay – Snorkeling Paradise near Cat Ba

• Location: Eastern side of Cat Ba Archipelago, Lan Ha Bay, Hai Phong Province

Lying adjacent to Cat Ba Island, Lan Ha Bay has an area of 76 km² and is home to 300 limestone islets and over 170 coral species. The best snorkeling and diving in Halong Bay are around Nam Cat Island and Monkey Island, where coral gardens develop beneath calm, turquoise water.

Ideal water conditions, moderate currents, minimal waves, and shallow reefs make snorkeling in Lan Ha Bay a prime option for families and beginner divers. There are also diving equipment rental facilities and beach facilities in Nam Cat for an all-day aquatic adventure.

Lan Ha Bay (Source: vn360)

Vung Ha Island – Hidden Coral Trails in Bai Tu Long

• Location: Between Vung Vieng Fishing Village and Luoi Liem Island, Halong City

Vung Ha Island is located in the center of Bai Tu Long Bay. The island is a treasure with aquarium-like clarity. The coral beds here are teeming with starfish, parrotfish, butterflyfish, and sea slugs, with 10–15 meters of visibility on a sunny day.

This is a great half-day snorkeling trip from Halong City for those based there. Visitors tend to combine a trip here with the nearby Vung Vieng Floating Village to provide guests with a mix of underwater adventure and local culture.

Vung Ha Island (Source: mrlinhadventure)

Cai Bau Island – Limestone Walls and Marine Mystique

• Location: Van Don District, Bai Tu Long Archipelago, Quang Ninh Province

One of the islands in the Van Don Island group, Cai Bau Island, offers a more demanding route for Halong Bay scuba diving. Being among the sites of limestone ridges that fall steeply into the sea, the dive site features underwater caves, deeper coral ledges, and a more abundant ecosystem of sea fans, soft coral, and tropical fish.

For certified divers, Cai Bau is a rare northern Vietnam location that offers advanced diving profiles, with depths ranging from 10 to 18 meters. It’s best accessed via private diving tours from Van Don pier or Hon Gai.

For certified divers, Cai Bau is among the limited northern Vietnam destinations that offer demanding diving profiles, from 10 to 18 meters deep. It’s best accessed via private diving tours from Van Don pier or Hon Gai.

Cai Bau Island (Source: vietdivers)

Co To Island – Coral Garden at Hong Van Beach

• Location: Co To District, Quang Ninh Province (2-hour speedboat from Cai Rong Port – Van Don)

Co To Island, particularly Hong Van Beach, offers some of the most vibrant coral landscapes in the North. The site has shallow, protected coral gardens that are home to clownfish, soft corals, and sea anemones, and is an ideal snorkeling and beginner dive site.

Water clarity is excellent year-round, especially from May to September. There is also rental gear and guided snorkeling tours available at Co To Park, perfect for travelers looking to mix relaxation with gentle adventure.

Co To Island (Source: vietnamtourism)

What to Expect: A Day on a Diving Tour in Halong Bay (Bai Tu Long Route)

07:30 – 08:00 | Hotel Pickup & Boarding at Bai Chay Marina

Start the day bright and early with a friendly pickup from your hotel in Halong City. Meet your certified diving guide at Bai Chay Marina, where you’ll be fitted with gear: oxygen tanks, wetsuits, diving masks, fins, life vests, all inspected to international safety standards.

We’ll then hop aboard a high-speed boat and begin our journey into Bai Tu Long Bay, the less crowded, more pristine section of Halong.

09:00 – 11:00 | Dive Session at Cong Do Island – Coral Reef Wonderland

• Location: Cong Do Island, Bai Tu Long Bay (25 km southeast of Bai Chay)

First is the stunning Cong Do Reef, which boasts rare red coral reefs, soft sea fans, and a multitude of marine life such as anemones, clams, and tropical fish. It has gentle currents and visibility of up to 12 meters, ideal for both novice and certified divers.

You’ll be guided into the reef zone for a 60-minute underwater exploration, supervised by licensed dive instructors. For snorkelers, float above a vibrant marine carpet just beneath the surface.

11:30 – 13:00 | Lunch & Chill at Vung Ha Island

• Location: Vung Ha Island, near Luoi Liem Islet

We sail northeast to Vung Ha Island, a virgin piece of reef and calm waters. Drop anchor near the island for a seafood lunch freshly cooked onboard: grilled shrimp, steamed clams, stir-fried vegetables, rice, and tropical fruit.

In the afternoon, enjoy some leisurely snorkeling in the nearby shallow waters or simply sunbathe on the deck amidst the surrounding limestone cliffs in every direction.

13:30 – 15:30 | Kayaking or Snorkeling – Vung Ha Lagoon

If you’re up for more adventure, grab a kayak or SUP board and paddle through the serene lagoon. Vung Ha has crystal-clear water and isolated coves where coral beds, sea cucumbers, and small reef fish make their home.

Take an optional second snorkeling here, perfect for getting that last look at Halong’s colorful reef life before we return.

16:00 – 18:00 | Return to Bai Chay – Sunset Cruise

Cruise to Halong City, passing by well-known formations like Dog Islet and Fighting Cock Rock. Enjoy tea on the upper deck while your guide summarizes the day’s spotting and gives eco-diving tips for future adventures.

Snorkeling At Vung Ha Lagoon (Source: pelago)

Best Time to Go Diving in Halong Bay

Best Months: May, June, September

These three months offer:

• Clean water (visibility 10–12 meters)
• Water temperatures of 25–29°C
• Fewer storms and lower tourist numbers
• Entity: Diving Season
  Attribute: Visibility
  Value: Best from May to September

During this period, you will get the best out of your scuba diving in Halong Bay, whether you snorkel shallow reefs or join a full Halong Bay diving excursion with Impress Travel.

When NOT to Dive

• Winter (November – February): Low water temperature less than 20°C, poor visibility
• Storm season (late July – early September): Weather becomes unpredictable and may cancel tours

Comparing: DIY Diving vs Booking a Tour in Halong Bay

Who Should and Should Not Join Diving Activities in Halong Bay

Who Should Dive

• Adventurous travelers aged 12 to 55 who like the sea
• Everybody with a little bit of swimming experience (you don’t need to be a strong swimmer)
• Underwater photography enthusiasts, especially in coral-rich waters like Cong Do or Nam Cat
• Energetic outdoor adventurers in generally good physical health

Who Should NOT Dive

• Children under 10 years old

• Pregnant women, since there is a risk of pressure
• People with heart, lung, or ear conditions (consult with your doctor before making a reservation)
• People under the influence of alcohol or heavily medicated
• Those who may panic when in water or have a phobia of enclosed areas

Responsible Diving – Preserving Halong’s Marine Beauty

Why Reef-Friendly Diving Matters

Coral reefs are alive, and some grow just a few centimeters a year. One single kick or touch can take years to heal from, or destroy it for good. That’s why all our diving Halong Bay Vietnam tours follow international guidelines for responsible diving.

What We Practice and Promote

• Never touch, stand on, or take anything from coral reefs
• Avoid sunscreens with oxybenzone or octinoxate, which harm aquatic life. Reef-safe sunscreen is encouraged
• All of our dive guides receive eco-diving procedure training, so your experience will be safe and sustainable
• We also support community-led coral conservation initiatives, especially in Cong Do,  where red coral reefs are being actively protected

Conclusion

From vibrant coral reefs to shimmering schools of tropical fish, diving Halong Bay offers a breathtaking underwater world waiting to be explored. Whether snorkeling in Lan Ha or diving deep off Cong Do, you’ll uncover the hidden side of Halong that few travelers ever experience.

With the best diving months between May and September, it’s now the ideal time to begin planning your adventure. Booking a tour Halong Bay Vietnam through Impress Travel ensures professional guidance, the best safety, and uncompromising respect for sea conservation.