Scuba diving is a popular adventure activity millions of people enjoy yearly. From exploring vibrant coral reefs to discovering exotic marine life, there’s a whole new world beneath the waves. But as with every water sport, there are certain risks involved. Most of these can be avoided with the right safety measures and precautions – but sometimes, things can take an unexpected turn.
Natural disasters like tsunamis can have a devastating impact on the coastal regions they affect. But what happens if you’re scuba diving when one hits? Being in the water during a tsunami can be extremely dangerous and even fatal.
In this article, we’ll look at what can happen if you’re scuba diving during a tsunami and how best to stay safe.
A tsunami is a succession of waves caused by an abrupt disturbance in the ocean. This disturbance can come from many sources, such as underwater earthquakes or volcanic eruptions. The bigger the earthquake or eruption, the larger and more powerful the waves will be. Tsunami waves can reach over 100m tall and can travel at speeds of up to 800km/h.
Tsunamis can also be categorized based on their distance from the source and the affected areas. There are three main types of tsunamis: local, regional, and distant.
1. Local Tsunami
A local tsunami is a type of tsunami that originates within 100km of the coastline. Local tsunamis are usually small in height but can be extremely destructive when they hit populated coastal areas. They can travel at high speeds and may hit the shore within minutes of the initial disturbance.
Local tsunamis are usually the most dangerous type of tsunami because they provide little to no time for evacuation.
2. Regional Tsunami
A regional tsunami is a type of tsunami that originates more than 100km but less than 1000km away from the coastline. The further away from the shore a tsunami begins, the slower it will be – but the waves will grow significantly higher as it travels from deep to shallow water.
Regional tsunamis give slightly more time to evacuate compared to local tsunamis.
3. Distant Tsunami
A distant tsunami is a type of tsunami that originates more than 1000km away from the coastline. They are also known as ‘ocean-wide’ tsunamis because they can travel across entire ocean basins and affect multiple countries.
Distant tsunamis can take several hours to reach the coastline, but they can be much larger and more destructive than local or regional tsunamis. Because they take longer to reach the shore, there is usually more time for evacuation and warning systems to be put in place.
Sometimes, there are warning signs that a tsunami is on its way. Depending on the type of tsunami, these signs can range from subtle changes in the ocean’s surface to loud rumbling noises and even visible waves.
Not all tsunamis have warning signs, but it’s important to know what to look for if you’re in the water when one strikes, to ensure you are not scuba diving during a tsunami:
Impending tsunamis can cause abrupt changes to the ocean, such as:
- Choppy waves
- Coastal waters rising or falling further than usual
- Incoming walls of water
- Severe water frothing
- Strong and sudden currents traveling to the shore
All of these indications can be signs that a tsunami is on the way. If you’re in the water and notice any of these movements, it’s important to get out as soon as possible and alert any other divers.
Tsunamis can be accompanied by loud rumbling noises similar to those of an oncoming train or thunder. If you hear a loud sound while underwater, you must act fast and get out immediately. This is why you must understand the signs of a tsunami – if you don’t, you might think the noise is something else and not realize it’s a tsunami.
If you are about to enter the ocean and feel any unusual ground motion, this could be a sign that a tsunami is on its way. Earthquakes can cause tsunamis, so if you feel the ground shaking or trembling beneath your feet, it could be a warning sign that a tsunami is coming.
The waves generated by a tsunami are often much more substantial than regular ocean swells, and they can be challenging to outswim – no matter how strong of a swimmer you are. If the tsunami is local, you may have little to no time to evacuate the water before the waves hit.
That said, it is believed the further out to sea you are, the safer you may be. This is because tsunami waves grow as they travel toward the shore. Official guidance suggests that if you’re in a boat, you should face toward the waves and travel away from the beach. Doing this can help get you away from the shallow coastline – where the tsunami will be strongest.
But what if you’re already in the water when a tsunami hits? Let’s take a look at what can potentially happen if you’re scuba diving during a tsunami:
You may notice increased currents deep underwater depending on how the water behaves. These currents can cause a ‘washing machine’ effect, where the water continually spins you around in circles. Rotoring currents like these can not just cause a diver to turn dangerously, but they can also pull you higher or deeper into the water.
Not only is this incredibly disorientating, but it can also cause decompression sickness.
Decompression sickness occurs when a diver ascends or descends too quickly, and their body’s gases expand, causing pain. If a ‘washing machine’ current is strong enough, it can cause severe decompression sickness – potentially leading to life-threatening situations.
If you are in particularly shallow waters when a tsunami hits, the waves can become so strong that it carries you back to shore. While this may sound good, it can be extremely dangerous. A tsunami wave can move you at high speeds, and hitting the shoreline unexpectedly can cause serious injuries.
Tsunamis can disrupt large amounts of sediment and cause debris to enter the water. Both of these situations can cause loss of visibility at varying levels. Suddenly having to navigate through murky water can be disorientating and can cause divers to become unaware of their location.
Quick-moving currents can easily separate divers from their boats or diving groups. Separation like this can cause divers to become lost or stranded – making it difficult to find their way back to safety.
Just like there’s a chance of being carried toward the shore, divers can also be swept out to sea. Scuba divers may become lost and drift into open water if this occurs. This can make it harder for help to find you and also increases the risk of hypothermia (depending on the water temperature) or exhaustion.
When the water constantly moves, it can be hard to control your body. This means you may have a higher chance of running into trees, rocks, or other debris in the water – especially if visibility is low.
The strong currents can also push you into underwater structures, such as coral reefs and shipwrecks. Hitting debris or underwater structures at any speed can cause serious harm to both yourself and your equipment.
Of course scuba diving during a tsunami is extremely dangerous, but there are also stories from some divers who were underwater during a tsunami and reported feeling nothing. Only when they returned to shore did they realize what had happened.
So it’s possible not to feel the effects of a tsunami if you are deep enough in the water or far away from the coast. It all depends on how powerful the tsunami is and where you are to it – tsunamis are not just surface waves; they can affect the entire water column.
You should not dive if there is any sign of an impending tsunami. But as we know, tsunamis can arrive with little to no warning. While a diver’s safety depends almost solely on how the water is behaving, there are a few tips to keep in mind that can help:
Familiarize yourself with the signs mentioned above to recognize tsunamis if they occur. While you may not be able to avoid the tsunami altogether, you can take measures to reduce your risk.
Every boat should have a marine radio to receive tsunami warnings and updates. Coastguards will broadcast warnings over the radio, so make sure you have one in your boat. This is not just useful for tsunamis but also for other emergencies.
One of the biggest dangers of a tsunami is being swept away from your group. Make sure you are in a group or with a buddy whenever you dive. If someone is caught in the current, the other divers can alert help and ensure a search and rescue team is sent out.
Tsunamis can cause widespread devastation on land, and there’s a chance you may have to stay on your boat for a day or two. A disaster supply kit onboard can help you stay alive in an emergency.
Your disaster supply kit should include everything you may need to survive at sea for a short while, such as:
- Basic medical supplies
- Communication devices (radio, phone, etc.)
- Emergency flares
- A whistle
If you’re about to embark on a dive and you can see or feel the force of a tsunami, the U.S. government recommends traveling in land and seeking high ground. If you’re not in the United States, familiarize yourself with your local government’s regulations and safety tips.
If you’re already in the water or on your boat and see a tsunami approaching, the best thing to do is try and go out to sea.
Face your boat in the direction of the waves and travel in that direction. According to the U.S. Government, you should aim for waters at least 180 feet deep. This is considered a safe depth. Stay away from the coastline until you receive communication that it is safe to return.
If you’re scuba diving and realize you’re caught in a tsunami, the most important thing is to stay calm. Panic and stress can make it harder to think clearly and make decisions. Instead, focus on the signs of a tsunami and assess your surroundings. Panicking also causes us to breathe quickly, which can use up our air faster.
Try to get back to your boat depending on how the water is behaving. Once in your boat, you can assess the situation and check for any warning signals on your marine radio.
If you have been swept away from your boat, stay calm and swim to the surface. The currents underwater can be incredibly strong and dangerous. If you can reach the water’s surface, you can visibly see any approaching waves. This can help you assess your surroundings better.
If you can’t safely return to your boat or the water’s surface, find something to hold on to – a rock or other anchor points can provide stability in the water. This can help stop you from being swept away by the current.
Tsunamis can cause a lot of debris to be swept up in the water. Debris can cause injury, so it’s essential to keep an eye out and avoid it as much as possible. We know this can be hard when visibility is low and abnormal water movements occur, but being aware of your surroundings can help.
If you can ascend to the surface but cannot get on your boat, find something that can float and hang on to it. While debris can cause injury if you’re unexpectedly hit by it, it can also provide something for you to grab onto and keep afloat.
Once at the surface, stay away from the shore and alert help if possible. Even after it seems a tsunami has passed, it can still be dangerous to approach the shore. Listen out for advice from authorities on when it is safe to return.
Tsunamis and storms are not the same, but it is still important to be aware of the dangers of both. Unexpected storms have caught out many divers while underwater, so it is vital to be mindful of the conditions before diving and be prepared for any eventuality.
You should always check the weather forecast before diving and be aware of any signs of a storm approaching. However, storms can appear unexpectedly without warning.
While the wind and rain may not disturb the underwater environment (depending on the severity), lightning can still be dangerous.
Lighting can strike the water or boat and potentially cause injury. If a storm appears while you are underwater, the best thing to do is abort the dive and resurface safely.
If you are caught scuba diving during a storm, you should do the following:
- Return to your boat immediately
- Go inside if your boat has a cabin
- Stay still and low to the ground if on a small boat without a cabin
- Avoid metal objects and electrical appliances
- Be aware of potential lightning strikes
- Keep an eye on the waves and return to shore if it is safe
If you need to decompress, do so safely – even if that means staying underwater and waiting for the storm to stop.
Some of the most beautiful dive sites worldwide are located in hurricane-prone areas. Many divers choose to travel to these destinations during hurricane season due to the lower price points and lack of tourists.
While diving during hurricane season isn’t unusual, you should under no circumstance scuba dive while a hurricane is actually present.
A hurricane is a tropical cyclone characterized by strong winds, heavy rain, and sometimes storm surges. Hurricanes can cause a lot of damage to the environment and can be dangerous. Oceans can be churned up and affected by the storm, rendering them unsafe for divers.
Always check the weather forecast before diving, and be aware of any signs of a hurricane approaching.
If you’re at a dive resort or on a liveaboard, abide by the rules and advice staff provide. They know the area better than anyone else and will advise you on the best course of action.
No one can predict the exact time and place when a tsunami will occur. However, earthquakes and other seismic events are known to trigger tsunamis. As such, authorities can monitor areas that are prone to earthquakes and provide warnings if a tsunami is likely.
Tsunamis can happen anywhere in the world, but some are more prone to them than others.
Depending on the location, these areas may be close to tectonic plates, oceanic trenches, and underwater volcanoes. The Pacific Ocean is particularly prone to tsunamis, especially around the ‘Ring of Fire.’ Still, other areas, including the Indian Ocean, the Caribbean Sea, and the Atlantic Ocean, can also see large-scale tsunami events.
Tsunamis can last several hours or even days. They travel as fast as 500mph, and the waves can be highly unpredictable. It entirely depends on the source of the tsunami and its intensity.
As previously mentioned, some scuba divers don’t even notice when a tsunami is occurring. These divers are very lucky and will most likely be unaffected.
Others may encounter strong currents, waves, and debris which can be hazardous. We cannot ignore the danger of a tsunami, and underwater activities are not recommended in these circumstances. This is why it is important to be aware of tsunami warning signs and heed advice from authorities.
Scuba divers should always be aware of their surroundings, especially when visiting locations that are prone to tsunamis. Safety should always come first in any situation, and diving during a tsunami is never a good idea.
Scuba diving is a great activity that can be enjoyed worldwide, but it is crucial to remain safe and know when to stay out of the water. Aside from tsunamis, avoid scuba diving during storms and hurricanes, and follow local authorities’ advice. This way, you can ensure your diving experience is safe and memorable!