A question that we’re often asked by those looking to do their first dives here at Big Blue Diving is how long does a dive on Koh Tao last? In this blog, we will try our best to answer that question, but of course, many different factors will influence the length of time that a dive will last including your size, your fitness, your depth and your excitement level.
Breathing Rate
Obviously the faster you breathe, the shorter your scuba dive on Koh Tao will be. After all, the time underwater is dictated by the amount of air in the diving cylinder or ‘tank’. So how can you extend your bottom time? Don’t breathe so fast, that’s how! Slow, relaxed breaths are the way forward here – exactly how you’re breathing right now.
Size of the Diver
Are you a big fatty wobbler, a 2-meter giant or a muscle-bound hero? Then you’re going to breathe more than smaller humans since you’re carrying a lot of extra weight compared to those damn slim people. It takes more energy and effort to move this mass around and that takes oxygen. A lot of it. It’s like they’re working out every time they move. I don’t recommend chopping off a limb before diving of course, but I imagine it would help.
Underwater Conditions
We all dream of scuba diving in crystal clear waters, gliding effortlessly through the water free of currents without a care in the world, but in reality, it isn’t always like that. There’s always a chance that the visibility may drop, which may make the diver a little nervous and that can often result in faster breathing. Tidal movement may also introduce an ocean current, which will put the diver in a situation where they need to kick harder, increasing the rate the diver is breathing – both of which will shorten the amount of time the diver gets underwater.
Excitement Level of the Scuba Diver
Many situations will make your heart beat faster including how excited you are. The faster your heart beats, the faster it can get more blood and oxygen to your muscles, leading to – you guessed it – shorter dive times due to the increased rate of breathing that goes hand in hand with heart rate. So we shouldn’t get excited? That may be difficult especially when diving for the first time, but with practice, a scuba diver can control this more and have a longer dive time. Calm and collected is what we aim for when scuba diving!
Depth of the Dive
Simply put, the length of your dive directly relates to the depth of your dive on Koh Tao. The deeper you dive, the denser breathing gases become (the more molecules are required to fill a given flexible space). Double the pressure (at 10 meters of seawater) and it takes twice as much gas to fill your lungs with each breath. Triple the pressure (at 20 meters of seawater) and it takes three times as much gas to fill your lungs. Therefore, the deeper you dive, the faster you will consume the air from your scuba tank no matter how much it can actually hold.
The Size of the Scuba Tank
There are varying sizes of scuba tanks used for diving and the size you’re given will affect how much air it can hold and how long the tank will last at a given depth. The most common sizes you’ll encounter are 12 litres and hold 200 bar (or thereabouts). In Europe, it’s also common to have the larger 15-litre tanks which should add about 10 minutes to your dive time from the standard 12-litre cylinders.
So how long does a scuba tank last? The average beginner diver’s air consumption in calm waters runs a tank close to empty in around 1 hour at 10 metres depth, compared to just a few minutes at 40 metres. Professional and very experienced divers can usually double this time through breathing and buoyancy control, and by minimizing the amount of movement underwater.
Quality of Instruction
I’ll never forget my first ever scuba diving experience on my Open Water Diver Course where my bitter old Scuba Diving Instructor shouted at us poor students repeatedly, got really angry when we messed up and generally just acted like an arse the whole time. He didn’t exactly inspire any of us new divers or calm us when we faced a challenging part of the Open Water Diver Course. To be honest, it seemed to us that we were wasting his valuable time and he’d rather be anywhere else but in the classroom with us.
When we were descending on the first ocean dive we were (no doubt due to the poor quality instruction we’d received) pretty bloody nervous, and felt ill-prepared for what we were about to encounter. Nervous divers, like the excited diver we talked about earlier, breathe a lot more hence have shorter dives – we lasted about 30 minutes only. Would a better instructor have been able to allay our fears, resulting in calmer divers? You’re damn right they would have!
Diving Technique
Anyone with a bit of scuba diving experience can tell you that there are a lot of divers out there with poor technique. Scuba divers will bump into you, constantly adjust their buoyancy, flap their hands around, kick as hard and fast as they can and often ruin the dive for everyone else in their group. The solution can often be quite simple; take the Perfect Buoyancy course offered at your local dive centre, or take the SSI or PADI Advanced Diver course where the instructor will really work on taking your diving technique to the next level, often leading to a large increase in bottom time for the newly competent scuba diver.
Speed of the Diver
When you’re active, your breathing can increase up to about 40-60 breaths a minute to cope with the extra demand on your body. The delivery of oxygen to your muscles also speeds up so they can do their job efficiently. This is all well and good if you’re a professional athlete, but while diving you want to try to maximize the time spent underwater by breathing slowly and calmly as much as you possibly can!
The key to this is to dive really slowly. Less movement leads to less oxygen being pumped to the muscles by the heart, so the breathing rate will also slow right down. We don’t want to be kicking constantly or darting around the dive site. If you aim to slowly glide around underwater as much as possible you’ll be amazed just how much longer your dives become!
What Can We Conclude?
The short answer is that a dive on Koh Tao lasts about 45 minutes to an hour!
If you want to know how to better consume your air consider taking the Advanced Diving Course.
