An Essential Skill for Drift Diving Around Gili Air

You are drifting comfortably along a reef when the current changes direction. A few minutes later, the dive site is behind you and the boat is no longer directly above your group.

This does not necessarily mean that anything has gone wrong. Drift diving is common around the Gili Islands, and dive boats often follow divers by watching their bubbles and anticipating the direction of the current.

However, before the group begins its final ascent, the boat crew must be able to identify where the divers are likely to surface. Other boats in the area should also be warned that divers are ascending underneath them.

That is where a surface marker buoy becomes essential.

A surface marker buoy is not simply another accessory to attach to your BCD. When correctly deployed, it makes divers more visible, helps the boat prepare for their recovery and provides a useful visual reference during the ascent.

But carrying one is not the same as knowing how to use one.

What Is a Surface Marker Buoy?

The terms SMB and DSMB are frequently used interchangeably, but technically they describe two slightly different pieces of equipment.

An SMB, or surface marker buoy, is normally inflated at the surface. It can help make a diver more visible after surfacing.

A DSMB, or delayed surface marker buoy, is designed so that it can be deployed from underwater. It is connected to a reel or spool and sent to the surface before the divers begin their ascent.

A DSMB usually has an overpressure valve that allows expanding gas to escape as the buoy rises. This is important because the gas inside the buoy expands as the surrounding pressure decreases. An ordinary surface-only SMB may not be designed to manage that expansion safely [1].

In everyday diving conversations, people often call both devices an “SMB.” In this article, however, DSMB refers specifically to the type that can be deployed from underwater.

Why DSMBs Matter Around the Gili Islands

The waters surrounding Gili Air, Gili Meno and Gili Trawangan are well known for drift diving.

Currents transport divers along coral slopes and across dive sites, allowing them to cover a large area without constantly swimming against the water. When the current is moderate and the dive is properly organized, this can create a relaxing and enjoyable experience.

However, a drifting group may finish its dive a considerable distance from where it entered the water. The boat therefore needs to follow the divers and identify their expected surfacing position.

SSI explains that DSMBs can be used to signal a diver’s location to people at the surface, particularly where strong currents make a drifting ascent more appropriate or where no fixed ascent line is available [2].

A deployed DSMB can:

• Show the dive boat where the group is ascending.
• Warn other vessels that divers are below the surface.
• Help the boat crew prepare for recovery.
• Provide the group with a visual reference during the ascent.
• Make divers easier to locate if they surface away from the planned position.

This is particularly valuable around busy tropical islands, where dive boats, passenger boats, fishing boats and private vessels may all use the same waters.

A DSMB does not create a protected area around the divers, and it never guarantees that every boat will see or avoid them. Divers must still listen for boat traffic, remain together and follow the instructions given during the dive briefing.

Nevertheless, being visible is considerably better than ascending without any surface signal.

Carrying an SMB Is Not Enough

Many certified divers own a DSMB and spool. They keep them clipped neatly to their BCD and carry them on every dive.

But when was the last time they actually practised deploying them?

A DSMB becomes a useful safety tool only when the diver can deploy it while maintaining:

• Neutral buoyancy.
• Depth control.
• Awareness of the surroundings.
• Control of the reel or spool.
• Contact with the buddy or dive group.
• A safe ascent position.

Deploying a DSMB can appear easy when demonstrated by an experienced dive professional. The diver unclips the buoy, prepares the spool, adds gas and releases it towards the surface.

In reality, several things are happening simultaneously.

The diver must manage buoyancy, avoid entanglement, monitor depth, maintain control of the line, prevent the spool from jamming and remain aware of other divers. If too much gas is added or the spool becomes trapped, the diver may be pulled upwards.

The British Sub-Aqua Club warns that DSMB deployment is a skill divers should practise regularly. Its safety guidance also states that the reel should not be attached to the diver because a jammed line could pull the diver towards the surface [3].

An SMB stored in your pocket cannot protect you if you do not know how to use it.

Buoyancy Control Comes First

Safe DSMB deployment depends heavily on good buoyancy.

A diver who needs both hands simply to remain at the correct depth is not ready to add another task. Looking down at a spool can also cause an inexperienced diver to lose awareness of depth and begin sinking or ascending.

When a DSMB is released, the gas inside it expands as it moves towards the surface. The diver must allow the line to run freely while remaining at a stable depth.

If the spool jams and the diver refuses to let go, the buoy can pull the diver upwards. A rapid ascent increases the risk of lung overexpansion injuries and decompression illness.

This is why the reel or spool must never be wrapped around the hand or attached to the diver. The diver should be able to release it immediately if necessary [3,4].

Good DSMB deployment is therefore not merely an equipment skill. It combines:

• Neutral buoyancy.
• Situational awareness.
• Equipment handling.
• Problem-solving.
• Ascent control.

This is also why neutral buoyancy should be learned from the beginning of a diver’s education. A diver who is comfortable and stable in midwater has a much stronger foundation for learning practical skills such as DSMB deployment.

Common DSMB Deployment Mistakes

Even experienced divers can make mistakes when they have not practised the skill recently.

Attaching the reel to the BCD

A diver may believe that clipping the reel to the BCD prevents it from being lost. Unfortunately, it can also prevent the diver from releasing it if the line jams or becomes caught.

The diver should always be able to let go of the entire system.

Wrapping the line around the hand

A line wrapped around a finger, wrist or hand can tighten very quickly as the buoy moves towards the surface. This may cause an injury or drag the diver upwards.

The line should remain controlled but never wrapped around the body.

Adding too much gas

The DSMB does not need to be completely filled at depth. Gas expands significantly while rising. Adding too much gas can create excessive upward force and make the deployment harder to control.

Losing buoyancy control

Some divers concentrate so intensely on the DSMB that they forget to monitor their depth. They may unknowingly sink, ascend or drift into another diver.

The DSMB should never become more important than maintaining control of the dive.

Using an unsuitable line length

The reel or spool must contain enough line for the depth from which the DSMB will be deployed. SSI specifically advises divers to confirm that sufficient line is available for the buoy to reach the surface [2].

Allowing loose line to accumulate

Loose line can become entangled around equipment, fins, coral or another diver. Keeping the line organized reduces this risk.

Practising for the first time in difficult conditions

A strong current, deep water or busy ascent is not the right environment for a diver’s first attempt. The skill should initially be practised under the direct supervision of a qualified professional in controlled conditions.

Who Deploys the DSMB During a Guided Dive?

During a normal guided dive around the Gili Islands, the Divemaster will usually deploy the DSMB for the group.

Once the buoy reaches the surface, the Divemaster controls the spool and uses the line as a visual reference while the group ascends and completes its safety stop.

Divers should remain close to the guide and follow the planned ascent procedure. They should not automatically deploy several additional DSMBs unless that procedure has been agreed upon during the briefing.

However, every certified diver should still consider carrying their own DSMB and spool.

Why?

Because groups can become separated.

Good organization, small groups, attentive guides and proper buddy procedures reduce this possibility, but they cannot eliminate it completely. Visibility can change, currents can split and divers can become distracted.

If a diver becomes separated from the group and follows the agreed lost-buddy procedure, that diver may eventually need to ascend without the Divemaster. Having a personal DSMB—and knowing how to use it—can make the diver much easier for the boat crew to locate.

SSI recommends an SMB for boat dives involving drift or significant surface traffic. It also notes that although the Divemaster should carry one, having your own is valuable if you become separated from the group [5].

Why Oceans 5 Requires Dive Professionals to Carry One

At Oceans 5 Gili Air, every Divemaster and instructor is required to carry an SMB and reel.

This is not optional equipment for a working dive professional.

Our Divemasters guide guests through an active marine environment where currents, weather, boat movements and underwater conditions can change. They must be prepared to manage a normal drifting ascent, an unexpected change in the dive plan or a situation in which the group surfaces somewhere different from the anticipated position.

Carrying the equipment is only part of that responsibility.

Oceans 5 trains its own Divemasters and expects them to practise deployment while maintaining neutral buoyancy and control. A professional should be able to manage the DSMB without losing awareness of guests, depth or environmental conditions.

The objective is not to perform an impressive-looking skill.

The objective is to keep the group organized and visible.

The DSMB Is Part of the Dive Plan

The decision to deploy a DSMB should not be improvised at the end of the dive.

Before entering the water, divers should understand:

• Who will deploy the DSMB.
• At approximately what depth it will be deployed.
• What the group should do during deployment.
• How the ascent will be organized.
• What to do if a diver becomes separated.
• Which surface signals are used.
• How the boat will approach the group.
• Whether the area has any special local procedures.

Divers should also examine the DSMB and spool before entering the water. A tangled line, damaged reel or incorrectly attached buoy is much easier to correct on the boat than underwater.

A good briefing creates shared expectations. Everyone knows who is responsible and how the group will respond.

Different Colours Can Have Different Meanings

Orange, red and yellow are among the most common DSMB colours because they are generally easy to see at the surface.

However, there is no universal recreational-diving rule that gives every colour the same meaning worldwide. In some technical-diving procedures, one colour may indicate a normal ascent while another signals a problem or requests assistance.

Any colour-based communication system must be discussed with the boat crew before the dive. A signal has no value if the people at the surface interpret it differently.

DAN recommends highly visible colours and notes that larger DSMBs are generally easier for surface support and other vessels to see, particularly when conditions are rough [1].

An SMB Does Not Replace Other Safety Equipment

A DSMB is an important visual signal, but it should not be the diver’s only method of attracting attention.

Once at the surface, a diver may also benefit from:

• A whistle.
• A signal mirror.
• A dive light or strobe in low light.
• A brightly coloured hood or equipment panel.
• An electronic location device where appropriate.
• Staying physically close to the buddy or group.

A DSMB is most effective while it remains upright. Divers should maintain appropriate tension on the line without attaching it to themselves.

Divers should never assume that carrying one signalling device makes them impossible to lose. Safety comes from combining planning, appropriate equipment, competent boat support, buddy awareness and properly practised skills.

Learn the Skill Before You Need It

The worst time to discover that you cannot deploy your DSMB is when you are separated from the group in a strong current.

Practise in calm, controlled conditions with a qualified instructor. Start shallow, concentrate on buoyancy and gradually build the ability to complete the deployment while remaining aware of your buddy and depth.

Divers returning after a long break may also include DSMB practice as part of a refresher, depending on their experience and the objectives of the session.

More experienced divers should not assume the skill will remain perfect forever. Equipment handling becomes less automatic when it is not regularly practised.

The British Sub-Aqua Club describes DSMB deployment as one of the skills that commonly goes wrong and advises divers to practise it regularly [3].

A Small Piece of Equipment With a Big Responsibility

An SMB or DSMB is relatively simple, compact and inexpensive. It fits inside a BCD pocket and may remain there for most of the dive.

But when the group is drifting, the dive plan changes or a diver becomes separated, it can become one of the most important pieces of equipment being carried.

Around the Gili Islands, currents are part of the diving experience. They bring movement, marine life and exciting drift dives, but they also require preparation and respect.

Every diver should understand what a DSMB does.

Every dive professional should be confident deploying one.

And every diver who carries one should practise using it before it is genuinely needed.

Because owning safety equipment is not enough.

You must also have the ability to use it calmly, correctly and while maintaining control.

Frequently Asked Questions

What is the difference between an SMB and a DSMB?

An SMB is generally inflated at the surface, while a DSMB is designed to be deployed from underwater. A DSMB normally includes an overpressure valve that allows expanding gas to escape as it rises [1].

The terms are often used interchangeably in everyday recreational diving.

Do I need an SMB when diving around the Gili Islands?

Your Divemaster should carry one during a guided dive, but carrying your own is strongly recommended—especially when drift diving or diving in areas with boat traffic. It can become particularly important if you become separated from the group.

Will the Divemaster deploy the SMB?

During most guided dives, the Divemaster will deploy the DSMB for the group. The procedure should be explained during the dive briefing.

Individual divers should still understand the process and know how to respond while the DSMB is being deployed.

Should every diver carry a DSMB?

It is good practice for every suitably trained diver to carry one. Even if the Divemaster normally deploys the group’s DSMB, a diver may need a personal signaling device after becoming separated.

Can I learn DSMB deployment during my Open Water course?

The exact course content depends on the training program and conditions. However, certified divers can practise DSMB deployment under professional supervision during continuing education, speciality training or an appropriate skills-refresher session.

Is deploying a DSMB difficult?

The basic procedure is not complicated, but performing it while neutrally buoyant requires practice. The diver must manage the DSMB, line, spool, depth, buoyancy and surrounding environment simultaneously.

At what depth should a DSMB be deployed?

The appropriate depth depends on the dive plan, training, conditions, equipment and local procedures. Divers should follow the method taught by their instructor and the instructions provided during the dive briefing.

Can I attach the DSMB reel to my BCD?

No. Safety guidance warns against attaching the reel or spool to yourself. If the line jams, becomes caught or is pulled by something at the surface, the diver must be able to release the complete system immediately [3,4].

Why should I not wrap the line around my hand?

The line may suddenly tighten while the DSMB rises. A line wrapped around a hand or finger can cause injury or pull the diver upwards.

Does an SMB guarantee that boats will avoid me?

No. A DSMB improves visibility, but it does not create a guaranteed exclusion zone. Divers must continue listening for boats, remaining with the group and following safe ascent procedures.

Can several divers deploy their DSMBs together?

Multiple lines in a small area can increase the risk of entanglement. During a guided dive, divers should follow the procedure explained by the Divemaster rather than automatically deploying several DSMBs at once.

How often should I practise DSMB deployment?

Regularly enough that the equipment and procedure remain familiar. If you cannot deploy it calmly while maintaining neutral buoyancy, depth and awareness, you should practise again with a qualified professional.

Does Oceans 5 require its Divemasters and instructors to carry an SMB?

Yes. Oceans 5 requires its Divemasters and instructors to carry an SMB and reel. Dive professionals must be prepared to mark the group’s position and organize a controlled ascent during local drift dives.

References

1. Divers Alert Network. “Popping the Question: What Is a DSMB?” Explains the differences between SMBs and DSMBs, their construction, visibility and their role in alerting surface support and boat traffic. DAN DSMB guidance
2. Scuba Schools International. “Surface Marker Buoy 101—All You Need to Know.” Explains how surface marker buoys and delayed surface marker buoys are used, including during drifting ascents and in areas without a fixed ascent line. SSI surface marker buoy guidance
3. British Sub-Aqua Club. “Safe Diving Guide: Equipment.” Advises divers to practise DSMB deployment regularly and warns against attaching the reel to the diver. BSAC equipment guidance
4. British Sub-Aqua Club. “Safe Use of Surface and Delayed Surface Marker Buoys.” Discusses entanglement, buoyancy control and the danger of attaching an SMB or DSMB reel to the diver. BSAC SMB and DSMB safety guidance
5. Scuba Schools International. “15 Essential Items to Take on Your Boat Dives.” Recommends an SMB for drift diving and areas with boat traffic and explains why individual divers should consider carrying one even when the Divemaster has one. SSI boat-diving equipment guidance