Surface Marker Buoy: What It Is & Why You Need One

The Unsung Hero of Dive Safety

A Surface Marker Buoy (SMB) might not be flashy, but it’s one of the most important pieces of gear a diver can carry. Whether you're diving from a boat, exploring a drift site, or just want to make sure you're visible at the surface, an SMB can help keep you safe, visible, and found. It's the kind of tool you may not think about until you need it.

What Is a Surface Marker Buoy?

An SMB is a brightly colored inflatable tube that floats upright at the surface to mark your location. It is often orange, yellow, or pink for high visibility. There are two main types:

Although the terms are often used interchangeably, they serve different functions and require different skills. On this site, when we say "carry an SMB," we mean a delayed SMB — a dSMB — that you deploy from depth during or before your ascent.

Why I Don’t Recommend SMBs (Get a dSMB Instead)

Basic SMBs are meant to be inflated at the surface or towed during the dive. They are often marketed toward newer divers because they seem simpler and cheaper, but they are not the right tool for most dive scenarios.

Here is why I strongly recommend skipping a surface-only SMB and going straight to a dSMB:

• Surface SMBs do not help you until you are already at the surface
  If you are separated, ascending in a current, or surfacing away from the boat, a basic SMB will not do anything to help others track your location during the critical ascent phase.
• You cannot use them to signal before surfacing
  A dSMB gives the boat or surface team a heads-up that you are on your way up before you ever break the surface. This is essential in drift diving or boat traffic.
• They are usually poor quality
  Many surface SMBs are open-ended tubes that flop over or do not stay upright. They are harder to see and less reliable than proper dSMBs.
• You will eventually need a dSMB anyway
  Nearly all dive training beyond the beginner level (Rescue, Advanced, technical) assumes you can safely deploy a dSMB. It is a core safety skill. Learn it now.
• Real-world usage favors dSMBs
  I have never once regretted carrying a dSMB. I have seen plenty of divers regret not having one ready to go at depth.

Bottom line: Skip the surface-only SMBs. Get a good dSMB, practice deploying it, and carry it on every dive.

Why Every Diver Needs One

Even in perfect conditions, a surface marker buoy adds critical safety and peace of mind. It helps others see you, supports safe ascents, and gives you an emergency signal option if something goes wrong.

• Boat Traffic Safety — An SMB helps boat captains and crew spot you from a distance, especially critical in busy or low-visibility areas.
• Drift Dive Tracking — In a current, your position can shift fast. Deploying an SMB before surfacing allows the boat to track you in real time.
• Solo or Separated Surfacing — If you become separated from your buddy or group, an SMB lets everyone spot you during the return.
• Required by Training Agencies — Agencies like SDI, SSI, and GUE all recommend or require carrying a dSMB on deeper, drift, or boat dives.

When You’ll Actually Use It

Some divers carry an SMB but rarely use it until the one day it matters. Here are common real-world situations where you will be glad you had one:

• Boat dive with no mooring line
• Drift dive with group separation
• Low visibility ascent
• Rough surface conditions
• Solo ascent or diver lost scenario
• Training site with surf zone entry or exit

If your first reaction to surfacing is "I hope they see me" — you need an SMB.

Choosing the Right Type

There’s a wide range of SMBs on the market, but for recreational use, start simple. Later, you can upgrade as your diving expands.

Learn to Use It Before You Need It

Carrying an SMB is only half the equation. If you have never deployed one before, or only practiced once in training, it is worth refreshing the skill in a controlled setting.

• Practice in a pool or shallow open water
• Try both surface and underwater deployment
• Learn how to manage line tension and spool control
• Test your inflation method (oral or LP hose)