How to use a diving surface marker buoy

Posted on (Updated on ). 5 Min Read
Scuba instructor with surface marker buoy

Diving surface marker buoys (SMB) are very useful and may even save your life during a dive.

Therefore, you should definitely know how to use them correctly!

It is also an essential skill for all divers no matter their experience so be sure to practice it.

In this article, you will learn why we use SMBs and how to deploy them underwater.

What is a diving surface marker buoy?

Diving buoys or Surface Marker Buoys (SMBs) are usually large, inflatable tubes divers carry on their dives. When inflated, they mark the location of a diver or a diving group on the surface. In order to be clearly seen, they are usually colorful and sometimes equipped with reflective materials.

As you can see, this is similar to the clothes of cyclists or runners in the dark to increase their visibility.

Step 1: The right time

Depending on the nature of your dive and the environment, it can make sense to inflate your diving buoy at the beginning of your dive.

For example, if you go shore diving in shallow water, boats may also come to the same beach.

They should definitely know that you are out there with your buddy!

During drift diving or river diving, it is important for the dive boat to know where the group is at.

Therefore, an SMB is usually set right at the beginning.

Surface Marker Buoy
A personal surface marker buoy is especially useful if no other buoys are in the water.

Sometimes you just dive your plan and then use the buoy at the end of the dive to make sure that no boats cross the spot where you resurface. Or just to show your dive boat where it can collect you.

In an emergency, the buoy can be used on the surface to attract attention by swinging it back and forth.

Step 2: Before inflating the SMB

Prepare your surface marker buoy and check your surroundings.

Before you inflate it, you should make sure that you are neutrally buoyed. Then take the SMB out of your BCD (buoyancy control device) and unpack it.

It is often stowed in a small package together with a reel. There is enough line on the reel for the buoy to come to the surface. So take both out of the package and make sure the SMB is attached to the end of the line.

Look up and check that there are no obstacles.

Make sure you are not tangled on the line before inflating it!

Step 3: Inflating the buoy

How you inflate the buoy depends on how it is built. Some are inflated with the mouth and others with your alternative air supply (octopus). No matter which one you use, it is important that you practice!

Many diving buoys have openings on the bottom through which you can fill in the air from your regulator.

Either you use the purge button on your octopus or you hold the opening above your regulator so that the buoy catches your air bubbles (when exhaling).

You can do this without taking your regulator out of your mouth! But it takes a little longer and, as we think, is more cumbersome than using the octopus.

There are also buoys that can be filled with the hose from your inflator. Just don’t forget to plug it back into your BCD when you’re done!

If you use such a buoy a lot, you can also attach a second inflator hose to the first stage of your regulator so that you don’t have to remove the hose from the BCD every time.

Scuba diver hovering underwater
Become neutrally buoyant before inflating the SMB!

However, if you inflate the buoy with your mouth, make sure you have enough air between breaths to blow out your regulator. You mustn’t hold your breath while doing this!

If you want to practice how to deploy a safety marker buoy during a scuba dive, check out the Dive Control Management specialty course at Social Diving or book a private practice session!

Good to know: At depths, you usually do not need a lot of air to bring your diving buoy to the surface because the gas expands on the way up.

Check out the 3 most important diving gas laws if you wonder why this is.

Step 4: Let go 😉

That may sound strange, but in the heat of the moment, many divers forget to let go of the buoy or line when inflating.

This could mean that you will be pulled up with it. This is of course not a good idea because it would make the ascent much too fast.

It is best to hold the reel lightly in your hand when you “shoot up” the buoy. This allows the leash to unwind in your hand without being pulled up.

Scuba instructor with surface marker buoy
A happy dive instructor with his surface marker buoy (SMB) 😃

Once it has reached the surface, you need to hold the line taut so that it is level in the water on the surface.

If you have trouble staying down with the buoy in hand, try taking some air out of the BCD or adding a little less air to the buoy next time.

Step 5: The ascent

To keep the line taut, slowly wind it up again on the ascent. A loose line can cause the buoy to fall sideways on the surface and allow air to escape.

Always climb at a safe pace and remember to take a safety stop!

Your dive computer will tell you if you ascend too fast.

Step 6: At the surface

When you reach the surface, make sure the buoy remains upright until the boat has picked you up.

Scuba divers at surface with surface marker buoy
It’s best to leave the SMB inflated until you are back on the boat.

That’s it! Simple, right? 😃


That’s all there is to deploying a surface marker buoy.

Practice this a few times in a safe environment before relying on it in open water.

Use the FREE scuba diving trip packing list before your next vacation and don’t forget your SMB. 😉

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Always dive with friends and happy bubbles. 😃



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