The first thing you need to consider is your health and the medical form.
Certain medical conditions may prevent you from diving, such as asthma and heart conditions. There are many more that could mean its unsafe for you to dive too so as you have not dived before please take a moment to have a look at the medical statement. In Thailand you only need a doctors clearance to dive if you have one of the listed conditions otherwise you can simply complete the form upon arrival. If you have one of the listed conditions, please be honest. It wont necessarily mean that you can’t dive but it does mean you need to see a doctor first. It is always better to see your own GP before leaving versus leaving it to chance here in Thailand. Your own doctor knows you better whereas here a local doctor is more likely to say no if in doubt. In some instances your GP may refer you to or ask you to consult with a doctor qualified in dive medicine so make sure you don’t leave this until the last minute.
You do need to have a reasonable fitness level to dive. You don’t need to be super fit but you do need to look after yourself. Diving does place physical demands on you and you will need an average level of stamina and fitness to complete the course.
You do also need to be able to swim. Participants need to complete a 200m swim or 300m snorkel but there is no time limit in which to complete this. Participants also need to be able to float for 10 mins too. If this is not in your level of comfort please do consult your dive centre for their recommendation as to how you can enjoy the ocean if your abilities are less than this.
If you have a fear of fish, the ocean, open water or water in general its worth considering if committing to the full open water course is the best place for you to start. Most dive centres offer snorkelling or a try diving experience of some kind. These will get you into the water with no pressure and give you the chance to see what you think first.
Make sure you have enough time to complete your diving. Remember you need to leave 24 hours in between your last dive and flying.