Open Water 20

with Hydronauts


Are you ready to become a certified scuba diver?

The best way to learn scuba diving is with the RAID Open Water 20 Course at Hydronauts Diving Resort. Koh Tao is surrounded by warm, tropical waters making it the premier location to learn how to scuba dive. 

With over 25 local sites you can discover coral gardens, shipwrecks, underwater pinnacles, and artificial conservation reefs. Scuba diving in the Gulf of Thailand is known for being consistently calm, with clear waters and ideal conditions for a relaxed and scenic experience.

No previous experience is required to participate in the 3.5-day open water diving course. You will learn everything you need to know before exploring the underwater world. 

 11,000 THB


Minimum age for Junior Open Water is 12-14 years and 15 for the Open Water 20 diving course.

Must be able to float in a pool for 10 minutes unassisted.

Must be able to swim 200 meters with no swim aids or be able to swim 300 meters using a mask, fins & snorkel.

Must be medically fit to scuba dive.

Step 1 -
Online Study

Begin your scuba diving course before you arrive with e-learning online! You will access all your RAID scuba diving course training manuals and quizzes using a secure login. Contact us to start your Open Water 20 diving course and e-learning today!

Step 2 -
Theory & Workshops

On arrival, you will meet your instructor to review your pre-completed scuba diving course e-learning. Once completed, your instructor will conduct a few workshops and lectures before teaching you how to assemble your diving equipment.

Step 3 -
Pool Training

Next, your instructor will go through all of the necessary skills to learn as a new diver. Together, you and your instructor will spend some time in the training pool with demonstrations and constructive feedback on your skills as you master them underwater. Throughout the pool session, you will be learning to control your buoyancy as this is the MOST important skill to master. Buoyancy control is how we stay at desired depths and neither float nor sink in the water column. 

Step 4 -
Open Water Dives

The Open Water 20 course consists of four dives in the ocean. The day after your pool training, you will finish all of your academic education and head out to sea. You will take our longtail boat straight from the beach to our dive boat to complete the first two ocean dives. These first two dives have a maximum depth of 12 meters, in which you will be demonstrating a portion of the skills from your confined session.

After the dives, it is time to head back to the resort to relax at our beach bar while you debrief with your instructor and log the dives. The next morning, you will be back out on the dive boat for the third and fourth dives in the open ocean. You will demonstrate your remaining skills and then be certified as an internationally recognized Open Water scuba diver!


Flying after your dives? Be sure to give yourself an 18-hour window after your final dive.

Need a place to stay? We are a beachfront diving resort! We offer rooms from mixed dorms, double bed rooms, family rooms, and bungalows for weekly or monthly rent! You can book a room here

Please keep hydrated. Remember to drink plenty of water before and after your dives.

Bring sunscreen (preferably reef safe) and apply it an hour before entering the sea to protect marine life.

Why Choose Hydronauts?​

RAID Instructors​

Our experienced instructors are hand-picked, highly trained, and passionate about scuba diving. We tailor each course and dive to your unique needs.

Beachfront Diving Resort​

Southwestern-facing property including a dive shop, hotel, training pool, cafe & restaurant, dive boat, and beach bar. We offer diving & accommodation packages for every budget.

Guaranteed Small Groups

We guarantee small groups of no more than four students to an instructor or dive guide so that you get the individual attention you deserve.

State-of-the-Art Equipment

We choose to dive and teach in Backplate & Wing BCD with a Long-hose, Short-hose regulator configuration favored by technical divers.

Dive Anywhere in the World

Upon completion of your RAID scuba diving course, you will be issued with an e-certification card that recognizes you as an internationally certified scuba diver.

Low Carbon Footprint

We make every effort to reduce our footprint and use of paper and plastic. All our course materials are hosted online giving you access for life.

Reserve your space now


Have another questions? Reach out to us!

Yes! We are a 3-star beachfront resort with a wide variety of room options. Our dorm rooms start at 280 THB and private accommodation starts at 500 THB. Message us and ask about our diving and accommodation packages today. 

Yes! You can begin your reading and quizzes before you get here but you will need to complete the workshops and exams with your instructor when you arrive. Contact us now to get started.

Explorer 30 is the next course we recommend after your Open Water 20 Course. This course will focus on improving your buoyancy, advance your understanding of dive planning, and allow you to dive on shipwrecks, deep sites, and maybe even diving at night. Get in touch with us to learn more.

Yes. All the answers are in the manuals for you to review anytime. Our approach to education is for students to comprehend and practice through repetition rather than focusing on textbook memorization. This ensures that your actions are informed and contextual. 

Yes! Check our Try Dive page or get in touch with us to learn more. We can’t wait to show you the underwater world and teach you to defy gravity.