Top 9 Things to do on a Surface Interval
August 17, 2023
When we do multiple scuba dives in one day, we need to take surface intervals. They help to keep us safe and avoid decompression sickness. Since decompression sickness is the biggest risk in scuba diving, we must do all we can to avoid it. By following some simple safety rules, including taking a surface interval, we can dive with peace of mind and stay well.
But with all this time on the boat in between dives, what can we do while we wait? Read on to find out why surface intervals are so important and what you can do during your surface intervals.
What is a surface interval?
If you are new to scuba diving you might be wondering what exactly a surface interval is, and why scuba divers do them. You learn all about how to dive safely in your Open Water Diver program, including how to plan dives and surface intervals.
Here is a brief explanation to give you an idea:
When we breathe air at depth for an extended amount of time our bodies accumulate nitrogen, which builds up more and more depending on how long we dive for, and how deep we dive.
This nitrogen buildup is not dangerous in low amounts and will off-gas safely as long as we follow basic scuba diving practices such as: Ascending slowly, performing a safety stop*, avoiding flying and going to altitude after scuba diving, and taking surface intervals.
*Staying at around 5m deep for three minutes at the end of a dive before exiting the water.
A surface interval is the gap of time that we spend on the surface, in between dives. The longer we spend on the surface, the more nitrogen gets off-gassed, and the longer/deeper the next dive can be.
If you did a deep first dive (18 - 30 meters/60 - 98 feet), you would need a longer surface interval than if you did a shallower dive (less than 18 meters/60 feet), especially if you want to do a deeper dive on the second dive, too.
It is so important to stay safe when scuba diving. Here are 4 Things You Should Avoid After Scuba Diving.
Why do surface intervals matter?
If a scuba diver was to skip a surface interval, this could lead to decompression sickness, which is brought on by nitrogen bubbles forming in the tissues of the body.
Signs and symptoms of decompression sickness include:
• Pain in the joints
• Dizziness
• Fatigue
• Nausea
• Paralysis
• In the worst cases, it can even cause death.
A dive computer or a dive table helps scuba divers to plan how long their surface interval should be, and how long they can dive safely at certain depths. Most surface intervals are between around 40 to 60 minutes.
What is the best way to spend this time on the boat in between dives? Here are some ideas.
Top 9 things to do during your surface interval
1. Check your computer/dive table
Your dive computer can tell you how long you need to wait on the surface before you can jump in for your next dive; you simply enter the depth and time you plan to dive for. The computer calculates your surface interval length by looking at the dive you just did, and how long you have had on the surface already. Easy!
If you like working old school, you can look at a dive table to figure this out, although tables tend to be much more conservative because they do not consider that you probably did not stay at the maximum depth for the entire dive. But it is good to err on the side of caution and stay safe.
2. Make friends
The great thing about scuba diving trips is that you have at least one thing in common with everyone else on board. This makes it extremely easy to make new friends and potential future dive buddies. Use the surface interval to swap dive stories, give dive trip recommendations, share photos and videos, and add each other on social media.
3. Get warm
Hypothermia is one of the main risks in scuba diving. It is easy to become too cold without even realizing it. If you do not get warm on the surface interval, you will become colder much faster on your next dive.
It can be tempting to stay in your wet wetsuit during the surface interval, but it is much better to take it off, wrap a towel around you, sit in the sunshine, or put a hoodie on. The warmer you can get on the surface interval, the more comfortable the next dive will feel. If you go cold water diving, keeping warm is even more important.
Top tip: If you feel the cold easily, keep a woolly hat with your dive kit and put it on straight away when you exit the water.
4. Hydrate
Dehydration can increase your risk of decompression sickness in scuba diving. It is very important to drink water before the dive, on the surface interval, and after the dive. A hot tea can help warm you up and hydrate you at the same time. Most dive boats will have drinking water available, but always make sure to pack your own just in case.
5. Have a snack
Scuba diving can make you feel tired. Although it is not comfortable to dive on a full stomach, have a small snack on your surface interval to keep your energy levels up. Some good snacks include fruit, biscuits, crackers, nuts and oats. Avoid greasy and spicy foods and avoid eating so much that you feel full.
Top tip: If you are going boat diving and are prone to motion sickness, make sure you still eat something during your surface intervals. A small amount of plain food can reduce symptoms.
6. Set up and check your equipment
Do not leave it until the last minute to set up your equipment for the next dive. It is important to set up and check your gear earlier so that you can ensure it is all working correctly, and nothing needs replacing or swapping.
Once you have exited the water after the first dive, get out of your wetsuit, get warm, grab a drink of water, and then set up your equipment ready for the next dive. Do this before you sit down and relax.
7. Replace your camera battery
There is nothing worse than embarking on dive number two, seeing a whale shark or manta ray, and having your camera flash "low battery". Avoid disappointment by packing a spare, fully charged camera battery that you can swap in the surface interval.
Memories last forever but they can fade and become less clear. It is so nice to have pictures and videos to look back on for years to come and to show friends and family.
8. Take a nap
As we talked about above, scuba diving can be tiring. Once you have hydrated and set up your gear for the next dive, there is nothing wrong with taking a power nap. It is not unusual on surface intervals to see a pile of scuba divers basking on the boat deck, soaking up the sunshine like a colony of seals. Take care not to get sunburnt though - slather on some reef-safe sunscreen.
9. Avoid freediving
Now that we have talked about all the things you cando on a surface interval, freediving is one thing that you definitely should not do.
It might be tempting to jump into the water on your surface interval for a quick snorkel. That is fine as long as you stay on the surface. However, it can be risky if you freedive down under the water.
This is because breath-hold diving can still affect the levels of nitrogen that you have built up on the previous dive. Descending and ascending in the water can cause the nitrogen to form bubbles and potentially lead to decompression sickness.
Always avoid freediving between scuba dives, and after your final dive; for 12 hours if you have done one dive, or 18 hours if you have done two or more dives (the same rules as for flying).
So, now you know how to stay safe and entertained on your surface intervals, discover where you want to dive next. SSI’s MyDiveGuide features global dive sites, destinations, and wildlife encounters to inspire you. You can check out MyDiveGuide here:
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