How Long Can a Scuba Diver Stay Underwater


How Long Can a Scuba Diver Stay Underwater

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There’s no reason not to explore the deep blue when our world is made up of 70% water. There’s so much more down under than what we can imagine, from different species of animals and plants to architectural ruins and possibly hidden treasures.

And what’s a more terrific way to experience this part of the world than scuba diving?

Whether you’re a beginner at scuba diving or a curious lurker with a neat interest, it’s typical to wonder how long a scuba diver can stay underwater.

How Long Can a Scuba Diver Stay Underwater?

With a limited amount of air, the time a scuba diver lasts underwater usually depends on their scuba tank. A standard diver using a standard tank of 80 cubic feet at a medium depth can last from 40 to 60 minutes.

When you reach this mark in a recreational dive of 40 feet or less, you should already be preparing to ascend to the surface to avoid running out of air.

Meanwhile, a more experienced scuba diver may be able to stay longer. This can be because they have further knowledge of what tanks to use and how to manage their air consumption.

However, there are more factors that influence your time underwater. Some of these factors relate to you as a diver, and some of them are equipment-based.

Factors that Can Influence How Long A Scuba Diver Stay Underwater

If you’re aiming to go beyond the average amount of time in scuba diving, you first need to understand the factors surrounding the activity.

From proper mindset, scuba gears, and the environment itself, here are the things that can influence the duration of your scuba diving:

1.   Breathing Frequency

It’s a common mistake for beginners to underestimate the need to know the proper ways to regulate breathing when scuba diving. Oxygen tanks supply you with air while underwater, but the air consumption is still not the same as it’s on land.

You’ll have to avoid quick and shallow breaths if you don’t want to end your dive too early. A rapid breathing pattern will instantly get you to the safety limit (500 PSI or 50 bar), which will run you out of air.

Instead, breathe in deep and slow patterns. While submerged, you’ll have to conserve as much oxygen as possible in the tank. A steady breathing technique will help you with this, resulting in a longer underwater experience.

2.   Tank Efficiency

The scuba tank is usually the first gear people picture when they hear about the sport of scuba diving. This is because it’s essentially your underwater breather.

The cylinder, typically steel or aluminum, acts as storage that keeps highly pressurized gases. The amount of these gases contributes to how long a scuba diver can stay under the surface. The larger the tank, the higher volume of air it carries.

Instead of the common 80-cubic foot size, a diver who aims to go for a deeper dive may choose a larger tank to last longer underwater.

At times, you may notice how there are technical divers that carry two tanks behind them. These two cylinders have individual regulators each so that if one tank malfunctions, a diver can easily access the other, resulting in more air to breathe and a faster reaction time while in the deep.

3.   Scuba Equipment

Besides the tanks, using the right scuba equipment can determine how long divers can stay underwater. For example, some gears can help you compensate for positive buoyancy and may enhance your control of maintaining neutral upthrust when diving.

There is also an apparatus that can regulate the scuba tank to turn the pressurized gas into breathable air. Meanwhile, having a gauge will tell you how much air you have left in your tank.

The more specialized gear you use, the longer you’ll be able to your stay underwater.

4.   No-Decompression Limit

A no-decompression limit (NDL) pertains to the maximum amount of time a scuba diver can spend at a particular depth.

As you dive deeper, your NDL will become shorter. Once you’ve reached your no-decompression limit, you need to ascend and make safety stops to finalize your dive.

It’s advisable not to exceed your NDL if you have no specialized decompression training. This is so you can avoid the risk of decompression sickness. However, if you’ve exceeded, you’ll need to perform decompression pauses while ascending to gradually release the absorbed nitrogen as you end your dive.

Your NDL varies on how deep you dive and how frequent your air consumption is. A dive computer is an excellent gear to have if you want to calculate your NDL. It can also assist you in tracking when and how long you should be doing your decompression stops while ascending.

5.   Diving Distance

The depth of the dive can affect the length of the scuba diver’s stay underwater. This is because as you dive deeper, the water pressure will influence the air that leaves the tank. This is why you’ll have to use more air at the bottom than when you’re on shallower parts of the dive.

Diving deeper will make your body absorb nitrogen quickly. This will cause your no-decompression limit to become shorter, leading to less time spent underwater.

6.   Water Temperature

The continuous change in water temperature can shorten the underwater time. Although the appropriate exposure suits should be able to block the temperature changes, the fact remains that our bodies aren’t designed to stay underwater for a long time.

The possibility of the cool temperature decreasing your body heat can prevent your plans of staying submerged for a long time. This can also accost the risk of hypothermia.

This is why it’s the best choice to pause your diving activity once you start to feel a bit too cold, even if you still have enough air in your tank.

7.   Planned Maximum Dive Time

A planned maximum dive time is required for scuba divers. They should plan to explore enough depth within a specific pace.

You’ll typically encounter this when you join an organized scuba diving trip, with a DM monitoring the diving activities. However, you can still incorporate this even if you’re solo diving.

Despite the many reasons for imposing a planned maximum dive time, the limit mainly focuses on the safety of the divers.

If there’s a collaborative agreement on the time when everyone should already be at the surface, then the DM can be alerted if something’s gone wrong. This is to manage a quick response to the possible risks of the sport.

8.   Experience

It’s only natural for a veteran scuba diver to stay underwater longer. Experience is the most obvious factor that affects someone’s ability to remain submerged over time.

This is because they’ve already been trained on the ins and outs of buoyancy control, proper breathing techniques, and gear selection.

In other words, the more you dive, the more you can stretch your diving time.

9.   Comfort and Enjoyment

The comfort you’ll find while underwater also plays a huge part in how long you can stay under the surface. This can refer to both physical convenience and mental ease.

If you experience physical discomfort with your suit or equipment, you’ll naturally want to return to the surface faster. Meanwhile, feeling anxious and too excited can cause your heart rate to increase, which in turn speeds up your breathing and your air consumption.

Not enjoying the dive due to the discomfort will prompt you to choose a shorter dive. However, following the training and procedures and keeping a calm mindset will let you enjoy the lengths of the underwater dive even more.

The Advantages and Disadvantages of Staying Underwater for a Longer Period

A great advantage of staying underwater for a longer period of time is the exploration of a world different from ours and seeing something particularly exciting.

Aside from that, scuba diving sport itself provides you with exercise that will enhance your health. These benefits include:

  • Cardiovascular and muscle work-outs
  • Developing flexibility and endurance
  • Optimizing air consumption
  • Acting as a stress reliever
  • Improving blood circulation and reducing blood pressure

Meanwhile, the disadvantages of staying underwater too long are the cost, the cold, dehydration, and hunger.

A longer underwater stay is equivalent to bigger tanks, which is far from cheap. However, the biggest disadvantage is the cold.

You wouldn’t be able to control the discomfort of the cool water unless you ascend to the surface. Furthermore, the length of your stay and the exhaustion of diving will eventually lead you to thirst and hunger.

Wrapping Up

The thought of staying long underwater while scuba diving is fun and thrilling. However, getting to the exciting part of the sport means you’ll have to understand the factors that can limit your time underwater.

It can be dangerous and unpredictable. Performing dive after dive will help you improve your techniques until you are experienced enough for a long underwater stay.

Jack Thompson

Jack Thompson, a scuba diving enthusiast from San Diego, has spent over a decade exploring the underwater world across the globe. Sharing his passion through captivating stories and informative articles, Jack aims to inspire others to embark on their own scuba diving adventures and uncover the ocean's hidden treasures. Follow Jack on Twitter, Pinterest, Reddit, and Facebook or email him at Jack@diving-info.com

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