A strange and potentially alarming event affected the Valencian coastline on Monday, 24 August, when the Mediterranean Sea suddenly retreated and then surged back along beaches and harbours.

One of the most striking measurements came from Gandia, where sea-level monitoring recorded a change of around 70 centimetres in just six minutes.

The event was a meteotsunami, sometimes known around the Mediterranean as a rissaga. Despite the name, this was not a conventional tsunami caused by an earthquake.

What happened in Gandia?

According to data from the sea-level monitoring network operated by Puertos del Estado, the water level at Gandia Port changed dramatically during the morning.

At approximately 09:06 on Monday, the recorded level was around +0.336 metres.

By 09:12, it had fallen to approximately –0.371 metres.

That represents a difference of roughly 70 centimetres in only six minutes.

For anyone standing on the beach, however, the most noticeable effect would not necessarily have been the precise height of the change. Instead, the sea could appear to suddenly pull away from the shoreline before returning again, producing strong and unusual currents.

Radio Gandia SER has also reported on the phenomenon, with meteorologist Juan Beneyto explaining that the event affected areas including Gandia and Xàbia. He stressed that although the word “meteotsunami” sounds alarming, these events are not generally destructive.

What is a meteotsunami?

A meteotsunami is different from the type of tsunami most people associate with major earthquakes.

Instead of an underwater earthquake displacing a huge amount of water, a meteotsunami is linked to rapid changes in atmospheric pressure and atmospheric gravity waves.

These changes can cause the sea surface to rise or fall rapidly. The effect can then become particularly noticeable in certain coastal areas, ports and bays where local geography can amplify the movement.

AEMET described the event affecting the Valencian coast as being associated with atmospheric gravity waves. The agency also pointed out that this isn’t a new phenomenon in the region.

Think of it rather like a sudden change in pressure being transferred to the sea. A relatively modest atmospheric disturbance can produce a much more noticeable movement of water when the conditions and coastal geography are right.

Gandia wasn’t the only place affected

The unusual sea movement was observed across several parts of the Valencian and Alicante coast.

Reports included Cullera, Dénia, Xàbia, Santa Pola, Elche, Torrevieja and Orihuela Costa, with the exact effects varying from one location to another.

In Dénia, sea levels changed by around 40–50 centimetres over a matter of minutes. The sudden movement also produced strong currents and briefly made conditions more difficult for boats entering the harbour.

At Xàbia, the retreat was particularly easy to see. Water pulled away from parts of the coastline, exposing areas that would normally be submerged, before returning again.

@informer.valencia

Esto ha ocurrido en Jávea… posible riesgo de meteosunami

♬ sonido original – INFORMER VALENCIA

AEMET reported atmospheric-pressure variations of up to around 4 hPa in Xàbia between approximately 10:10 and 10:20 on Monday morning.

Santa Pola sees water reach the road

Further south, the phenomenon was particularly noticeable at Santa Pola.

At Playa Lisa and Gran Playa, the sea first retreated and subsequently advanced much further up the beach than normal.

The water reached towards Avenida Blasco Ibáñez, resulting in the local police temporarily stopping traffic as a precaution.

There were reports of boats and floating structures being affected, but the event did not result in widespread serious damage or major injuries.

@elche7tv 🌊 Primero el mar se retira y después vuelve a avanzar sobre la costa. Es el fenómeno que se vivió ayer en Santa Pola. El agua se retiró de forma repentina en varios puntos, dejando al descubierto zonas normalmente sumergidas, para después recuperar su nivel. En Playa Lisa, el mar llegó hasta la primera línea y obligó a cortar durante varias horas un tramo de la avenida Blasco Ibáñez. 👉 AEMET explica que se trata de un meteotsunami, un fenómeno de origen meteorológico que puede provocar oscilaciones bruscas del nivel del mar. 💬 ¿Viste este extraño comportamiento del mar en Santa Pola? Cuéntanos dónde. 🎙️ Eduardo Díez 🎦 MJ Rubio #SantaPola #Meteotsunami #PlayaLisa #AEMET #Alicante ♬ so original – Elche7tv

Was it dangerous?

A meteotsunami should not be confused with the sort of destructive tsunami associated with major earthquakes, but that doesn’t mean sudden changes in sea level are completely harmless.

Rapid movements of water can produce strong currents, which can be hazardous to swimmers and small boats. People close to the water could also be caught out if the sea suddenly moves further inland.

The best advice is therefore fairly simple: if the sea suddenly starts behaving strangely, move away from the shoreline and wait for conditions to settle.

Don’t walk out onto newly exposed rocks or seabed simply because the water has temporarily disappeared. The sea can return just as quickly.

This has happened before

AEMET says that meteotsunamis are not a new phenomenon on the Mediterranean coast.

A similar event occurred on 23 July 2017, when sudden rises in sea level were reported around Torrevieja, the Marina de Elche, Santa Pola and El Campello.

The Mediterranean is particularly capable of producing these events because of its geography and the interaction between atmospheric conditions and relatively enclosed coastal areas.

The most famous examples occur around the Balearic Islands, particularly at Ciutadella in Menorca, where the phenomenon is known as a rissaga.

So, should people on Gandia’s beaches be worried?

For the vast majority of beachgoers, there is no reason to panic because of Monday’s event.

The episode was unusual and impressive, but it was not an earthquake-generated tsunami heading towards the Costa Blanca.

The important lesson is simply that the Mediterranean can occasionally move very quickly when unusual atmospheric conditions occur.

And in Gandia, the monitoring equipment has provided an impressive reminder of just how quickly that can happen: around 70 centimetres of sea-level variation in only six minutes.

For anyone who was on the Gandia coast that morning, the sea may have looked relatively ordinary. Further along the coast, however, people were watching the shoreline retreat and return within minutes.

That makes Monday’s event a fascinating example of how atmospheric conditions can produce dramatic changes in the Mediterranean — without an earthquake, major storm or traditional tsunami being involved.

Did you see the meteotsunami?

If you were on Gandia, Xeraco, Cullera, Dénia, Xàbia or another nearby beach on Monday morning and saw the sea suddenly retreat or surge forward, we’d be interested to hear what you experienced.

The event is also a reminder that unusual weather and coastal phenomena can happen very quickly — even on an apparently normal summer morning on the Costa Blanca.