Can You Swim During a Thunderstorm? And Why Do Fish Never Get Struck by Lightning?

Swimming during a thunderstorm is one of those activities that most people instinctively know is a bad idea. But why exactly is it dangerous? And while we’re at it, why don’t fish get struck by lightning when they’re in the water? Let’s dive into the science, myths, and oddities surrounding thunderstorms and water.

The Danger of Swimming During a Thunderstorm

1. Water Conducts Electricity

Water is an excellent conductor of electricity, especially when it contains dissolved minerals like salt. When lightning strikes a body of water, the electrical current spreads out across the surface and can travel significant distances. If you’re swimming, you become part of that conductive path, putting you at risk of electrocution.

2. Lightning Strikes Are Unpredictable

Lightning can strike miles away from the actual storm. Even if the storm seems far off, you could still be in danger. The “30-30 rule” is often recommended: if you hear thunder within 30 seconds of seeing lightning, seek shelter immediately, and wait at least 30 minutes after the last thunderclap before resuming outdoor activities.

3. Open Water Increases Vulnerability

Swimming in open water, like a lake or ocean, makes you the tallest object in a flat area, increasing your chances of being struck. While lightning tends to strike the highest point, water’s conductivity means the danger is amplified even if you’re not the tallest object.

4. The Myth of Safety in Freshwater

Some people believe that freshwater is safer than saltwater during a thunderstorm because it’s less conductive. While it’s true that saltwater conducts electricity better, freshwater is still highly dangerous during a storm. The difference in conductivity is negligible when it comes to the massive energy of a lightning strike.

Why Don’t Fish Get Struck by Lightning?

1. Lightning Prefers the Surface

When lightning strikes water, most of the energy disperses horizontally across the surface rather than penetrating deeply. Fish swimming below the surface are generally safe from the immediate effects of a strike.

2. Water’s Conductivity Protects Them

The conductivity of water helps dissipate the electrical charge quickly. While the surface might experience a surge, the current weakens as it spreads out, reducing the risk to marine life below.

3. Fish Are Not Grounded

For a creature to be electrocuted, it needs to complete an electrical circuit. Fish are surrounded by water, which means they don’t provide a path to ground. Humans, on the other hand, are often partially out of the water or in contact with the ground, making them more vulnerable.

4. Lightning Strikes Are Rare in Deep Water

Statistically, lightning is more likely to strike land than open water. Even when it does strike water, the vastness of oceans and lakes means the odds of it hitting near fish are incredibly low.

The Oddities of Thunderstorms and Water

1. Ball Lightning Over Water

There are rare reports of ball lightning—a mysterious, glowing sphere of light—appearing over bodies of water during thunderstorms. Scientists still don’t fully understand this phenomenon, but it adds an eerie layer to the relationship between lightning and water.

2. Thunderstorm-Induced Waves

Thunderstorms can create powerful winds that generate large waves, even in otherwise calm waters. These waves can be dangerous for swimmers and boaters, adding another layer of risk during a storm.

3. The Sound of Thunder on Water

Thunder sounds different over water due to the way sound waves travel. The flat surface of water can cause echoes and make thunder seem louder and more prolonged, adding to the intensity of the experience.

What Should You Do If You’re Caught in a Thunderstorm While Swimming?

1. Get Out of the Water Immediately The moment you hear thunder or see lightning, exit the water as quickly as possible. Don’t wait for the storm to get closer.

2. Seek Shelter Find a sturdy building or a fully enclosed vehicle. Avoid small structures like picnic shelters, which offer little protection.

3. Avoid Tall Objects If you’re on land, stay away from tall trees, poles, or other objects that could attract lightning.

4. Stay Low If no shelter is available, crouch low to the ground with your feet close together. This minimizes your contact with the ground and reduces the risk of a ground current affecting you.

FAQs

Q: Can lightning strike a swimming pool?

A: Yes, lightning can strike a swimming pool. If you’re in or near the pool during a thunderstorm, you’re at risk of electrocution.

Q: Is it safe to swim indoors during a thunderstorm?

A: Indoor pools are generally safe during a thunderstorm, as long as the building is properly grounded and you’re not in contact with metal fixtures or water.

Q: Why does lightning sometimes make the water glow?

A: This phenomenon, known as “St. Elmo’s Fire,” occurs when the electrical charge from a storm ionizes the air around objects, creating a faint glow. It’s rare but can happen over water.

Q: Can fish sense thunderstorms?

A: Some studies suggest that fish can detect changes in atmospheric pressure and electrical fields, which might allow them to sense an approaching storm.

Q: What happens if lightning strikes a boat?

A: If lightning strikes a boat, the electrical current will travel through the hull and into the water. Modern boats are often equipped with lightning protection systems to minimize damage and risk to passengers.

Thunderstorms are a powerful reminder of nature’s unpredictability. While swimming during a storm is undeniably risky, understanding the science behind it can help you make safer choices. And as for fish? They’ve evolved to live in an environment where lightning is just another part of life—albeit a rare and distant one.