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Why You Should Dive With An SMB

One of the most important safety aspects when diving is to ensure boat traffic is aware there are divers underwater and even more important – there are divers ascending. A surface marker buoy (SMB) shows boats that there are divers in the water and helps your own boat spot you as you ascend from a dive. A SMB is basically a small balloon that you inflate towards the end of a dive to warn passing boat traffic divers will surface shortly. This small piece of scuba equipment is an essential tool to ensure diver safety when underwater or on the surface.

My Dive Guide Has An SMB, Why Should I Bother?

PADI DM candidates deploying DSMB.

I completed my PADI Divemaster Course (DM) in 2019 with Downbelow Adventures and as a PADI DM in training you are required to own your own Surface Marker Buoy (SMB).

After completing my course, I have never dived without one as it is one of the most invaluable tool a diver should have. It is cheap and pack away easily and a life saver in a tricky situation. 

Fast forward to June 2020, I went on a diving trip with my friends. A few joked around saying they felt safe since there was PADI Pro within the group. During one particular dive when we were ascending, the current was so strong that three of us got swept away from our dive guide and two other buddies – we lost sight of them. Immediately, I deployed my own SMB as I instructed my buddies to stay close to me. Fortunately, thanks to my fluorescent orange buoy, the boat captain spotted us and picked us up straight away. Where was the dive guide? He and the other two divers were located about 50 metres away from where we surfaced. 

This event triggered a few questions among my dive buddies. What if they got separated and they were left to ascend alone? They were all experienced PADI AOW divers but they have always relied on dive guides at the end of every end dive, not thinking that they would get split up. I advised them to be independent and self-sufficient. This way, you know that you are going to make a safe ascent no matter what, even if the unexpected occurs. Since then, a few of them have now purchased their own DSMB!


The two main types of surface markers are the delayed surface marker buoy (DSMB) also known as the safety sausage, and the surface marker buoy (SMB). The DSMB is simply an inflatable tube that you send up to the surface from underwater as you begin your safety stop. This highlights your position in the water to boats and helps your own boat keep track of you. It can also act as a visual reference for you during your ascent.

You can inflate an SMB at the beginning of a drift dive and hold onto it during the dive so that your boat can easily follow along. This is a much more effective method for the boat driver than trying to follow your bubbles — not an easy task in even small waves. Either type of surface marker also allows your spotter to see you far more easily if you drift a little farther from your boat. If you become lost, you can use your SMB as a signalling device to say that you need assistance by holding it horizontally above your head.

The Basics – How to Deploy a DSMB

To perform the task underwater….
• Take out the SMB tube and unroll it making sure the string stays clear of your legs and away from any corals.
• Open up the bottom of the tube and use your 2nd stage alternate air source to purge air inside, remember the air will expand as the tube raises so no need to fill completely.
• Let go and watch as it makes it way to the surface, grab hold of string and pull down slightly to make SMB stand up tall on the surface.

Tips On Purchasing An SMB

If you are a keen active diver then purchasing your own SMB should be one of the first pieces of equipment you buy. But what makes a good SMB?

Example of a finger reel.

Firstly, it should be made from strong material that is unlikely to pop if overinflated. It should be around 6 foot long, the taller the better, it needs to be able to rise above any waves or swell. A lot of SMB’s will come with a string attached. These strings are usually around 5-6m in length which would barely stretch from your safety stop. I recommend a finger reel and attach that to either the sausage part of the SMB or the end of the string. This will enable you to deploy from depth.

If you are interested in purchasing an SMB, please contact our Dive Shop Manager, Karen at our Downbelow Dive Shop, KK Times Square and come check them out!