What Is Surface Interval In Scuba Diving?


Whether you decide to dive off a watercraft or from the shore, you will probably do more than one plunge during the day. But did you know that every time you make a dive, the level of nitrogen in your bloodstream rises? That’s why you need to take a break between dives to help your body dismiss the unwanted gas, and this pause is known as a surface interval.

Surface interval is simply the period a scuba diver stays out of the water after a dive to rejuvenate before taking the next dive. The nitrogen absorbed by the diver’s body during the first plunge is expelled at this time, which increases the duration they can remain below the water’s surface in the succeeding dives.

When Do You Start And End Your Surface Interval?

You begin your surface interval when you reach the water’s surface and are no longer breathing from your scuba regulator. In fact, your dive computer will start calculating your surface interval as soon as you get to the surface.

This period ends when you descend to begin your next plunge. During this time, you will still have some nitrogen left in your body from preceding dives. You will therefore need to calculate your residue nitrogen time and pressure group to find out the amount of nitrogen remaining in your body before the next dive. This can easily be done with a surface interval calculator.

A surface interval should last anywhere between ten minutes and an hour. Experts recommend a duration of an hour or longer. A sufficiently longer pause will ensure that your body releases as much nitrogen as possible.

Residue Nitrogen

During a dive, your body takes in nitrogen. This is because nitrogen is what constitutes the majority of the air in your scuba tank. While nitrogen keeps you alive underwater, a high concentration of the gas in your bloodstream could put you at risk of nitrogen narcosis, a common scuba diver’s health condition that alters their mental state.

The reason why you need a pause between dives is to help you release nitrogen from your body. Unfortunately, it takes hours to completely expel the gas after a dive, which means that you will still have some of it in your bloodstream when beginning repetitive dives. Consequently, nitrogen levels will continue to rise after every dive, which will reduce the amount of time you can stay underwater during those dives.

One way to reduce scuba diving dangers and risks is to take control of the nitrogen that accumulates in your body. Surface intervals will help you make more dives safely. During this time, you offgas a huge amount of nitrogen from your body increasing your underwater time in consecutive dives. It would be completely impossible for a diver to do more than one dive without surface intervals.

Keeping Track Of Your Surface Interval

After a dive, nitrogen can hide in your body for many hours. That’s why it is recommended that recreational divers planning to fly stay for at least twelve hours after single dives and about twenty hours after consecutive dives.

A surface interval calculator will help you determine the amount of nitrogen remaining in your body. If you are a recreational diver, however, you can consider yourself nitrogen free after eight hours regardless of how aggressive your dive was. For less intense diving, the surface interval could be shorter.

Aggressive dives will get you depleting your scuba tank faster than gentle dives and if you don’t know how to save air when diving, then you will find yourself ascending to the surface more often.  It is important that you beef up your scuba diving breathing techniques, as this will help you control the amount of air you consume and at the same time lower your surface interval. You want to spend more time underwater, not waste it on the surface.

What Should You Do On Your Surface Interval?


A surface interval is meant for rest and restoration. Diving, like any other activity that works your muscles, can leave your body stressed. Maintaining buoyancy control, handling equipment, and exploring the foreign environment while at the same time staying warm while diving can all affect your body. It would therefore be smart to treat your surface interval as a time for respite and recuperation. Here are a few things you can do to get the most out of your break.

1. Rehydrate

The reason why it is always advisable to refill your water bottles when heading out on the beach is to curb dehydration. Underwater, you may not sweat very much but things can be a little different on the surface especially if you are diving in hot weather.

Drink at least one liter of water and if possible, have an energy drink too. Avoid alcohol, caffeinated beverages, or any other drink that will affect your ability to drive safely.

2. Eat A Snack Or Light Meal

A snack or light meal will get your energy levels restored. Avoid potato chips and other salty munchies that will make you dehydrated. Have nuts and fruits instead.

Keep heavy meals at bay, as these will get your digestive system working more than necessary. Foods that cause heartburns or make you gassy should also be avoided.

3. Plan The Next Dive

Take some time to think about the previous dive. Check your air consumption and see what you can do to save more air in the next dives. This could also be the perfect time to clear your scuba mask of water, if any, repair any scuba gear that needs fixing, and acquire any equipment you may have missed during your first dive.

You might also like: What Is Residual Nitrogen Time (RNT) In Scuba Diving?

4. Rest And Unwind

Scuba diving requires a clear mind. Set aside some quiet time to relax physically and mentally.

Take a few minutes nap if you wish. Read a good book if you have one. Swing from your hammock – just anything to keep your body and mind relaxed. Strenuous exercises are not recommended during surface intervals.

Globo Surf Overview

Scuba diving is a thrilling activity. It gets you seeing a wide variety of water creatures, reconnects you with Mother Nature, and have you experiencing marine life in an entirely new light.

However, you must take surface intervals between dives and calculate the amount of nitrogen in your system before taking the next dive. During this time, focus on restoring your body regardless of how fit you are. Drink plenty of fluids, eat light snacks, and get your body to rest. This will give it the energy it needs for subsequent dives, which will make them safer and more comfortable.

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