The old saying goes that lightning never strikes twice… but when it does strike, it can do so with catastrophic results. While the majority of lightning strikes hit the land, it is still possible for the sea to be affected: NASA research shows that deep ocean areas are less likely to be struck, with those nearer the coast more likely to be hit.

For swimmers, water sports enthusiasts and boat owners, this can clearly be a cause for concern but what really does happen when lightning strikes the sea?

On land, the impact of a lightning strike tends to be vertical, with each bolt striking its target and heading in a downwards direction. Water, however, acts as a strong conductor of electricity and behaves differently to solid materials. On hitting the water, lightning spreads horizontally: it’s not just what’s at the point of impact that’s at risk but anything that finds itself in the surrounding areas too. Fish, boats, swimmers, divers – they can all be impacted.

It tends to be objects or living creatures at the surface of the water that are most likely to be affected: generally, fish will not be killed by lightning strikes as they tend to swim deeper than surface level. Swimmers, paddle boarders and surfers, however, can act as the point of least resistance for a lightning bolt – much like a person standing in the middle of an open space such as a field or a park. Diving down beneath the surface may prove a temporary solution but it’s unlikely that a human would be able to dive deep enough or for long enough to avoid the potential danger.

Lightning is more likely to strike closer to the land, so the recommendation for those who are unable to get to shore when a storm hits is to head further out to sea. For those close to the shore, the best thing to do is to exit the water as quickly as possible and find shelter – if there is no shelter available, crouch into a ball as opposed to lying flat.

For boat owners, the best way to avoid the risk of being struck by lightning while at sea is to fit the vessel with a lightning conductor. These devices direct the charge away from the vessel and directly into the sea, thus passenger areas of the vessel and vital equipment are protected. The use of electronics during a lightning storm should be avoided if possible – except, of course, in the case of emergency.

Lightning attacks can have devastating consequences for both natural and manmade structures alike – but some of these can be avoided. Lightning Strike Ltd supplies and installs lightning defence and electrical earthing systems – as recommended by BS 7430, lightning protection earthing systems use a wide range of materials, in various configurations, to achieve the maximum resistance level of 10 ohms or less.

Lightning strikes are likely to increase due to global warming – are you prepared?