Encountering Explosives – What You Should Know

by Henry Berkowitz:

Explosives present a unique hazard to divers and knowing what to look for, what to do, and what not to do if you encounter a situation that involves explosives, is critical.  Generally, explosives can be broken down into two types: unexploded ordinance and naval mines.  While it is possible to come across explosives in both fresh and salt water throughout the world, there are certain locations where the risk is increased.  A general understanding of these munitions is crucial for all divers.


There are two types of explosive hazards that a diver may encounter, Unexploded Ordinance (UXO) and Naval Mines.  A basic understanding is helpful for the identification of potential risks.  UXO is any type of explosive that has failed to explode as intended; typically this would be in the form of bombs or rockets. There is also the possibility of encountering industrial explosives.  Industrial explosives may have been used to unearth rock in a quarry or to destroy unneeded items. Naval Mines, on the other hand, are intended for water borne use and can be highly sensitive.

Naval Mines come in a variety of types and shapes.  There are four types of mines: seismic, acoustic, magnetic, and contact.  They will be shaped as either cylinders or balls. The name of each type of mine describes what will trigger it.  Seismic mines are intended to detonate due to the vibrations of a ship passing over it.  Acoustic mines are sensitive to noise and bubbles.  Magnetic mines respond to the magnetic signature of a ship’s hull.  Contact mines activate in direct contact, and typically are ball shaped with spikes.

Explosions under water create a unique circumstance. On the surface, explosions cause shock waves of force to move through the air. These shock waves can go great distances but are to some degree reflected by the tight cellular structure of the human body if they hit a victim. Under water, similar shock waves are created during an explosion that move a shorter distance in comparison, but maintain a higher level of pressure. Under water, pressure is not absorbed, which means the blast effect could move through a person causing immense damage.

What to do

If you encounter a suspected explosive of any kind – your dive is over.  Remember to stay calm, turn 180 degrees away from danger and begin a safe ascent while swimming away from the site.  Try to remember some basic information to pass on to authorities: note the depth, location, and description of the object in question.  Once you safely surface, exit the water and notify local authorities as soon as possible.

What NOT to do

It is equally important to understand what NOT to do in this situation.  First and foremost, do not approach or touch any type of suspected ordinance – ever.  Even fresh water is a harsh environment and because of this, there exists the potential for explosives to become unpredictable.  Also, refrain from increasing your signature in the water by limiting: noise, bubbles, or radio transmissions (if applicable).

While it is possible to encounter explosives all over the world, there are specific locations to be aware of.  The Mariana Islands have a high concentration of UXO while the Persian Gulf has increased risks with naval mines.  Quarries and mines are examples of fresh water locations with a risk from industrial explosives.  Mines and UXO can be found anywhere in the water column.  Contact mines typically float on the surface, while other types will rest on the bottom or be tethered.  Typically UXO will sink to the bottom.

If you ever find yourself in a situation involving explosives, remember to stay calm and end the dive in a safe fashion.  Report the hazard to the authorities with as much of a location and description as possible.   Explosives are dangerous, even more so in the water, do not approach or handle any suspected item, ever.  If you are interested in learning more about recognizing explosives, dealing with explosives, and managing a post-blast environment, ERDI has a set of classes available taught by experts on this subject matter.  Please be careful and make safe dives!

Henry Berkowitz – Air Hogs Scuba, Garner, NC

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