A deep diving license in Thailand, usually the PADI Deep Diver course, trains you to dive to 40 metres in 4 training dives, well beyond the 18-metre limit of Open Water and the 30 metres of Advanced Open Water. It opens up Thailand’s best deep sites, such as the King Cruiser wreck near Phuket at about 32 metres, in warm 28 to 30°C water with good visibility.
Thailand is where many people fall in love with diving. Most start with Open Water, a great ticket to adventure but capped at 18 metres, and many of the country’s most spectacular sites lie a little deeper. Here is what the next step involves and whether it is worth it.
At a Glance
- Depth limits (PADI): Open Water 18 m; Advanced Open Water 30 m; Deep Diver 40 m
- Deep Diver course: 4 dives, usually over 2 days; prerequisite Adventure Diver or Advanced
- Water temperature: About 28 to 30°C year-round
- Andaman season: Mid-October to mid-May for the Similan and Surin parks
- Key deep site near Phuket: King Cruiser wreck, upright at about 32 m
In This Guide
- What the Licence Lets You Do
- Unlock the Best Dive Sites
- Why Train in Thailand
- Is It Worth It?
- Where to Go Deep
- Choosing a Dive School
- Safety Basics
- Where to Stay
- Frequently Asked Questions
- Sources
What a Deep Diving License Lets You Do
Recreational certifications come with depth limits. With PADI, Open Water divers can go to 18 metres, Advanced Open Water divers to 30 metres, and Deep Divers to 40 metres, the recreational limit. Other agencies such as SSI have similar courses.
The Deep Diver course teaches you to plan deep dives, manage your gas supply, and recognise and handle nitrogen narcosis, according to PADI. It usually takes 4 dives over 2 days, going progressively deeper.
Unlock the Best Dive Sites
The main reason to go deep is access. Many of Thailand’s best wrecks and pinnacles sit below 18 metres, so without deeper training you only see them from above.
Take the King Cruiser near Phuket: an 85-metre car ferry that struck Anemone Reef on 4 May 1997 and sank with everyone rescued. It now sits upright on sand at about 32 metres, around 26 km east of Phuket, covered in soft corals and schools of snapper and fusiliers. Open Water divers can only look down on it; deeper training lets you explore the hull.
Hin Daeng and Hin Muang, south of Koh Lanta, drop to more than 60 metres, and their deeper walls hold the best soft corals and the best chance of manta rays and whale sharks.
Why Thailand Is the Perfect Classroom
Deep courses elsewhere can be cold and dark. In Thailand you descend into water of about 28 to 30°C, often with good visibility, and schools run courses almost every day.
- Theory: dive planning, gas management and nitrogen narcosis.
- Practice: 4 dives, usually over 2 days, gradually going deeper.
- Real sites: you train on proper dive sites, such as South Tip at Racha Noi from Phuket or Chumphon Pinnacle near Koh Tao.
Is a Deep Diving License Worth It?
For most divers who plan to dive again, yes. Two days of training turns the sites you have already heard about, like the King Cruiser, Richelieu Rock’s deeper sections and the Andaman pinnacles, from look-from-above sites into proper dives, and dive operators can put you on more trips.
It is less useful if you only dive once in a while, get cold or anxious easily, or mostly enjoy shallow reefs, where colours are brighter and bottom time is longer. Advanced Open Water, which includes one deep dive, is a good middle step.
Where to Go Deep
Once qualified, these are the places to use it (see our deep diving spots in Thailand for more):
- Phuket: the King Cruiser wreck, and South Tip at Racha Noi, with deep boulders and currents that attract manta and eagle rays.
- Similan Islands: granite boulder dives with deeper sections, open mid-October to mid-May; boats leave from Thap Lamu.
- Surin Islands: Richelieu Rock, famous for macro life and whale shark sightings, reached on liveaboards or from Khuraburi.
- Koh Lanta: Hin Daeng and Hin Muang, deep walls with big pelagic chances.
- Koh Tao (Gulf): Chumphon and Southwest Pinnacles, good for first dives below 20 metres.
For trips from Phuket, see our island hopping guide.
Choosing a Dive School
Phuket, Koh Tao and Koh Lanta all have many schools, and course prices vary with the school, the boat and the sites, so compare what is included rather than the headline price (as of September 2026). Useful questions to ask:
- Are the 4 training dives on real deep sites, and how many students are there per instructor?
- Is equipment rental, the certification fee and national park fees included?
- Does the school use a dive computer for each student, and what is the maximum group size on the boat?
- Can the course be combined with fun dives on the same trips to save days?
Read recent reviews that mention safety briefings and equipment condition, and choose a school affiliated with a recognised agency such as PADI or SSI so your card is accepted worldwide.
Deep Diving Safety Basics
Deeper dives mean shorter no-decompression limits and faster air use. A few rules keep them safe:
- Stay within your training and your computer’s limits, and ascend slowly with a safety stop.
- Watch for narcosis: if you feel confused or overconfident, ascend a few metres.
- Get dive insurance that covers the depth you dive to.
- Leave at least 18 to 24 hours between your last dive and flying.
If anything feels wrong after a dive, such as joint pain, numbness or unusual tiredness, tell your instructor straight away. Phuket has hyperbaric chambers for treating decompression sickness, and dive insurance covers the cost.
Where to Stay After the Dive
Most Phuket dive boats leave from Chalong Pier in the south, so staying in Rawai, Chalong or near Phuket Town keeps early starts short.
This is where we at Silqhaus come into the picture. Silqhaus, a Phuket and Pattaya holiday-rental company, has Sava Villa in Rawai and villas near Phuket Town, a short drive from Chalong Pier, plus apartments in Bang Tao. There is space to rinse and dry your gear, and booking direct is always at least 10% below Airbnb and Booking.com for the same home and dates.
Frequently Asked Questions
How deep can you dive with Open Water in Thailand?
18 metres with PADI Open Water, 30 metres with Advanced Open Water, and 40 metres with the Deep Diver specialty.
How long does the Deep Diver course take?
Usually 2 days, with 4 training dives that go progressively deeper.
Do I need a deep certification for the King Cruiser wreck?
It sits at about 32 metres, so operators generally require Advanced Open Water or deep training to explore it.
When is the best time to dive in the Andaman Sea?
Mid-October to mid-May, when the Similan and Surin national parks are open and the sea is calmer.
