Shallow Water Blackout

So you have been scuba diving or freediving for a while, got your skills down, and decided to go for a record in the 80m-200m-300m dive range. Or maybe you’re just 5 meters underwater when everything turns pitch black. What just happened? The technical word for this phenomenon is shallow water blackout. It’s pretty common among divers and can be quite dangerous if not handled correctly. If there is one thing that is certain about it, you don’t want to experience it.

What is shallow water blackout?

In this article, we’ll talk about what the hell shallow water blackout is and how to prevent it. We will also discuss the symptoms and treatments for it.

What is a shallow water blackout?

A shallow water blackout is a hell type of drowning that results in the loss of consciousness and drowning. It is thought to be caused by the sudden drop in oxygen levels in the blood, followed by a rapid decline in heart rate which could lead to death.

SWB has been studied since at least 1959 when it was first recognized as an issue for scuba divers. In this case, shallow refers to relative depth; SWB occurs when you dive deeper than about 10 meters (33 feet) for longer than 60 seconds but not quite long enough for full decompression stops.

What are the Causes of it?

It is a condition that can occur when a scuba diver rapidly ascends from the water. It causes a partial or complete loss of consciousness due to a lack of oxygen in the blood. This happens because their lungs cannot take in enough breathable air as they go up, causing symptoms such as dizziness and disorientation.

The exact cause of shallow water blackout isn’t known but is thought to be linked to two factors: rapid ascent, and/or rapid changes in depth (often referred to as ‘hard stops’). It’s also possible that there may not actually be any direct link at all between these factors and SWB; rather it could simply be caused by low levels of carbon dioxide (CO2) in your bloodstream when you’re underwater for long periods of time – though this is still under investigation by scientists today!

What to do if you suspect shallow water blackout

If you suspect someone is suffering from a shallow water blackout, the most important thing you can do is call for help.

Once you’ve done that, keep the person’s head above water and stay with them until help arrives.

Do NOT give them CPR or attempt to resuscitate them. It does not result in drowning; it just causes a person’s heart rate and breathing to slow down dramatically which can cause them to pass out underwater before they drown.

Unless you are an experienced swimmer who has safely rescued others from drowning before, DO NOT try to swim this person back to shore yourself—you will likely end up drowning as well!

Symptoms of shallow water blackout

  • Dizziness
  • Unconsciousness
  • Loss of control of arms and legs
  • Loss of consciousness


If you want to avoid it, there are several things you can do:

  • Dive with a buddy. If your buddy is also in trouble, it’s easier for them to help if you’re both on the surface.
  • Don’t dive alone. If something goes wrong underwater and no one else is around to help, it will be too late by then.
  • Don’t dive when tired or sick (or drunk). Your body may not be able to handle the strain of diving under these conditions.
  • Don’t dive when stressed or under the influence of drugs or alcohol (or any other substance). Stress and drugs can impair your judgment and make it harder for your body to respond appropriately if something goes wrong while diving in shallow water


  • Call for help. You must call for emergency assistance at once.
  • Apply CPR. First priority is to give the victim oxygen, so start providing artificial respiration (ART). When you do this, pinch the nostrils closed and cover victim’s mouth with yours, creating an airtight seal around your lips. Breathe into them two times (out of every five seconds), which is about 12 breaths per minute. If this fails to restore normal breathing, continue until EMS arrives or they regain consciousness and can breathe on their own again—about 20 minutes in total—but remember that if they have been submerged longer than 30 minutes it may be too late!
  • Get victim to safety immediately after CPR has been performed properly; do not move them unless absolutely necessary because any movement could cause more damage than what was already done by drowning itself! Keep them warm by wrapping them up tightly in blankets or clothing when possible; do not give fluids until EMS arrives because doing so could lead directly back toward death due to complications caused by hypothermia due any time spent underwater without proper protection from cold temperatures (such as being dressed appropriately). Also make sure there are no injuries present before moving forward: broken bones require immediate attention before resuming any treatment plan laid out prior.”

Scuba diving shallow water blackout

Scuba diving shallow water blackout is a medical emergency that occurs when a diver surfaces too quickly from a dive. The diver loses consciousness and sinks to the bottom. The condition can be fatal, with death usually resulting from drowning or asphyxiation by inhalation of vomit into the lungs.

Free diving shallow water blackout

It is a condition that can occur if you dive from the surface without having enough time to get your body acclimated to the pressure of diving. It’s also known as “Shallow Water Drowning”, and it’s a risk for spearfishing, free diving, and snorkeling.

It’s caused when you breathe in large amounts of water before having a chance to adjust your body for pressure changes underwater. Most commonly, this happens when people hit their heads on the bottom while swimming or diving too deep without being prepared for it. The effects are similar to how you feel after holding your breath too long: lightheadedness and confusion among other symptoms such as nausea or tingling in hands/feet/face (arms/legs).

Spearfishing shallow water blackout

Spearfishing can be a dangerous sport. The most common danger is shallow water blackout, which can lead to drowning. Spearfishermen must be extremely careful when diving for fish as well as avoiding injury from sharp objects and coral reefs.

To understand how it works, it’s important to know what spearfishing is. Spearfishing involves hunting underwater with a speargun or harpoon gun from the surface of the water. This sport requires divers to hold their breath while they enter the water, then swim down and retrieve their prey before surfacing again with it in hand.

The most common cause of shallow-water blackouts is hyperventilation (breathing too much), but there are several other causes as well:

  • The increased carbon dioxide concentration that results from hyperventilating too rapidly
  • Dehydration results in reduced levels of dissolved oxygen in your bloodstream which makes you feel dizzy and lightheaded while swimming around looking for food
  • Being fatigued by doing strenuous exercises like spearfishing

Drowning is just one of the dangers inherent in scuba diving

Drowning is just one of the dangers inherent in scuba diving. Another, which can occur even when you’re only a few feet underwater, is a shallow water blackout.

It occurs when breathing rates are too low to supply enough oxygen for your body’s needs during a dive. It can happen at any depth and doesn’t require a struggle. You could be enjoying an easy dive when it happens. The resulting lack of oxygen causes your brain to starve for energy and blackout for up to several minutes before you regain consciousness. If you’re underwater without any form of flotation device or gear and can’t swim upwards yourself, this could lead to drowning.


Shallow water blackout is a serious and potentially fatal condition. The best way to prevent form it is to be aware of the signs and symptoms and know how to respond in case of an emergency. If you suspect someone has suffered from SWB, seek medical attention immediately.