On Monday, 24 August 2026, a water level fluctuation of up to 1.44 metres was recorded in the harbour of Ciutadella. The phenomenon was also visible in Mallorca: in Port d’Alcúdia, water flowed as far as the area around the beachside restaurants, whilst further notable fluctuations were reported in Port d’Andratx, Port de Sóller and Port Adriano.
During the night of Thursday to Friday, 28 August 2026, another Rissaga struck the Bay of Santandria, west of Ciutadella. The wave flooded the beach and reached the ground floors of hotels and commercial premises. The fire service and police had to pump out the water and temporarily close access roads.
Mini-tsunami in Mallorca
What is a Rissaga?
A Rissaga – usually known internationally as a meteotsunami – is caused by rapid fluctuations in air pressure, which are often associated with thunderstorm lines, weather fronts or rapid atmospheric disturbances. The air pressure sets the water’s surface in motion, resulting in the formation of a long-period wave.
If, under the right conditions, this wave encounters water that is becoming shallower, it can grow significantly in size. In narrow, long and shallow harbour basins, there is an additional effect: the water oscillates back and forth, much like in a bath. Experts refer to this as harbour resonance. This combination makes Ciutadella particularly vulnerable. The narrow, shallow natural harbour has a natural period of around ten minutes, which can be greatly amplified by incoming waves.
Unlike a tsunami following a seaquake, a ‘Rissaga’ is not preceded by an earthquake. It can occur in seemingly calm weather, but creates dangerous currents in the harbour: first the water level drops rapidly, then the water surges back with great force. For mooring lines, jetties, mooring ropes and boats in berths, this can become a problem within a matter of minutes.
How a Rissaga is created
Why Ciutadella is particularly at risk
Tidal surges are not a new phenomenon in the Balearic Islands. However, Ciutadella is regarded as one of the world’s best-known locations for particularly severe meteorological fluctuations in sea level. Research findings show that atmospheric pressure waves, the water depth off the coast, the Menorca Channel and the shape of the harbour can interact in an unfavourable way there.
For skippers, such fluctuations can result in fenders suddenly hanging too high or too low, lines slipping or becoming taut, and boats coming into contact with jetties, dolmens or neighbouring boats. In shallow bays, there is also a risk of strong inflows and outflows.
This video explains the effect clearly
How skippers prepare
In the event of a Rissaga warning, skippers should not regard their mooring as a safe haven. It is crucial to allow the boat sufficient room to manoeuvre without it being able to strike the jetty or quay wall.
- Actively monitor warnings: Before and during a sailing trip in the Balearic Islands, check the regional Aemet warnings, harbour information and advice from the marinas. In the case of Menorca, take warnings of unusual tidal fluctuations seriously, even if the wind and waves appear harmless at first.
- Check the mooring lines: Position the lines so that they can function when the water level rises and falls sharply. Check the abrasion protection and allow for sufficient slack. Lines that are too short and pulled too tight can be subjected to considerable loads in the event of a sudden rise in water level.
- Position the mudguards low and wide: Fenders must still provide protection between the hull and the quay wall, even when the water level is significantly lower. Keep extra fenders to hand in tight berths and at fixed jetties.
- Don’t let it run out unnecessarily: Strong cross-currents can develop in a narrow harbour entrance or bay. Those who are securely moored should avoid manoeuvres until the harbour or the authorities give the all-clear.
- Re-evaluating anchorages: In shallow, narrow bays or those facing the open sea, the swell can become particularly unpleasant. If a warning is in force, it is better to choose a sheltered harbour with reliable information.
- Inform the crew and neighbouring vessels: If the water level falls or rises noticeably quickly, take immediate action, keep an eye on the mooring lines and keep unauthorised people away from quay walls, bathing jetties and boat ramps.
For charter crews, the Rissaga incident is yet another reason not to base weather and port planning in the Balearic Islands solely on wind strength and wave height. In Ciutadella in particular, if a warning is in place, sufficient time should be allowed for an alternative route or an extra day in port.
Book recommendations
Cruising Guide to the Balearic Islands covers Mallorca, Menorca, Cabrera, Ibiza, Espalmador and Formentera. With around 130 charts and harbour plans, as well as information on nautical conditions, provisioning options and shore excursions, it serves as a practical planning aid for motorboat owners. This guide is particularly useful for trips between Menorca and Mallorca, helping you to plan your destinations, stages and harbour stops more thoroughly.
Meteorology explains in an accessible way how water sports enthusiasts use weather charts, wind, clouds, sea state and tides to inform their decisions. The book also covers the formation of severe weather and the rules of conduct during thunderstorms and heavy swells. It thus complements a local sailing guide by providing the essential background knowledge needed to better interpret weather developments whilst on board.
Have you ever experienced sudden changes in water levels in Mallorca, Menorca or any other sailing area? What measures have proved effective at your mooring?
Lars Bolle
Chief Editor Digital