Close this search box.

Oceanic posidonia, the secret of Mallorca’s waters

Posidonia oceanica plays an extremely important and we would say almost crucial role in the waters of Mallorca and the Balearic Islands in general, due to its high levels of productivity, high biodiversity and importance in the protection and stability of the coastline.

As you know, the waters of the Balearic Islands are superb. They have an almost fluorescent blue hue, on some beaches more than others. Because of this and other attractions that the island has, Mallorca has become one of the most popular tourist destinations in the western Mediterranean.

Posidonia oceanica meadows

The Posidonia oceanica meadows are the main reason for the white sandy beaches and crystal clear waters that we have in Mallorca. They form a large underwater forest of enormous environmental value, as they trap sediment and thus contribute to the cleaning of the water.

The Posidonia oceanica is an aquatic plant – but note: plant, not algae – endemic to Mallorca and the longest living creature on the planet, at 100,000 years old. It has a stem, roots, leaves, flowers and fruit, and plays an important role in sediment dynamics.

An intricate network of biological relationships is established around this underwater forest, where more than 1,500 species of fauna and flora coexist, a perfect indicator of the quality of our waters.

What does Posidonia oceanica contribute to the sea?

  • Captures CO2 and releases oxygen: by photosynthesising, Posidonia captures carbon dioxide and releases oxygen, and one hectare of Posidonia captures as much carbon as up to 15 hectares of Amazon rainforest.
  • It keeps the sand on the beaches: it retains the sand from the foraminiferal animals that leave their shells behind when they die, creating over time and through erosion the fine white sand of the beaches.
  • Dune protection: its roots and rhizomes retain sediment from the coastline, preventing currents from washing sand away from the shore and protecting the coast from erosion in autumn storms.
  • Marine fauna habitat: it is a refuge and hiding place for a large number of fish, crustaceans and molluscs. Ocean grasslands are home to 400 different types of plant species and 1000 types of animals.
  • Caring for the seabed: The leaves, which can be up to 1.5 metres long in summer, fall in autumn and are washed ashore by storms, thus stabilising the funds, reducing the effect of swell, wind and settling the sand on the beaches.

Why are the beaches of the Balearic Islands so beautiful and blue?

The blue colour of the waters of Mallorca, Menorca, Ibiza and Formentera, which ranges from the dullest to the most electric shades of blue, is mainly determined by the following:

  • The transparency of its waters, which have a lack of suspended sediments, facilitating the penetration of light.
  • The amount of white sandy bottoms that act as mirrors reflecting the light.
  • The luminous intensity that predominates in Mallorca and throughout the Balearic archipelago.

Other determining factors are also the mixed effect of reflections, scattering and absorption of light, as well as water depth, sand, algae and suspended matter.

Beaches such as Es Trenc, Playa de Muro or Ses Covetes are a clear example of transparent waters, since being shallow beaches the reflection and dispersion of light is less powerful, so the colour of the water is almost colourless. It should also be added that the water in Es Trenc is particularly clean.

On the other hand, if we go to some beaches in the north, such as those of Cala Barques and Cala Figuera, which have deeper soils, the interaction of the water molecules with the light rays is more powerful, leaving a pattern of “blue spots” in the water and highlighting the blue spots. famous turquoise of the beaches of Mallorca.

Cove of Cala Barques in Cala San Vicente
Cala Barques with deeper waters

The colour of the water in Mallorca also changes depending on the area. For example, the water in the Puerto de Sóller area is sometimes a little scary and this is due to its yellowish green colour caused by phytoplankton, a micro-organism that grows in waters without currents and more temperate.

The beaches and coves of Mallorca have a look that has nothing to envy to the beaches of the Caribbean, and the Posidonia oceanica is the main reason why our beaches are so paradisiacal, as it keeps the water clean.

Preservation and care of posidonia oceanica

In Spain, Posidonia oceanica meadows have been protected as a habitat since 1995 and as a species since 2011. Since 1999, the Posidonia oceanica meadows of Mallorca and the Balearic Islands have been a UNESCO World Heritage Site. In 2018, the Balearic Government also approved a decree to make human activity compatible with the conservation of the meadows.

Many studies warn that these posidonia meadows are being severely damaged by human action, especially due to:

  • The anchoring of boats, whose anchors and chains drag the seabed.
  • Marine pollution.
  • Waste water discharges.
  • Sand mining and dredging.
  • The presence of invasive species.
  • Fishing practices.
  • Climate change.

What can I do to protect posidonia?

For us, our island comes first and taking care of it is the most important thing. So we encourage you to take care of it too.

Enjoying the island responsibly is possible and tourism is compatible with the preservation of Posidonia, as long as you take certain things into account:

  • If you decide to rent a boat in Mallorca, do not drop anchor on the posidonia meadows. To do this, we provide you with the GOIB Posidonia App, from the Balearic Government, where you can consult the distribution of the Posidonia oceanica meadows that surround Mallorca and anchor in the island’s waters without damaging the meadows.
  • Don’t throw rubbish or waste into the sea, and if you find yourself on a virgin beach like Cala Varques or Es Carbó, which do not have any kind of service, take your rubbish with you!
  • If you dive or snorkel, avoid touching the meadows and make sure that your diving equipment does not drag on the seabed.
  • Use environmentally friendly sun creams.
  • Notify the authorities if you detect non-compliance with these rules by others.

Together, we can all do our bit to save Posidonia. If you follow these tips you will be contributing to the present and future environmental conservation of an invaluable environment.

Have we helped you to understand the value of Posidonia oceanica in Mallorca and the rest of the islands of the archipelago? We end this article with a quote we heard the other day that is perfect for you:

“You love what you know”

Picture of Yo soy Mallorca
Yo soy Mallorca

Was this information useful to you? Share it!


Some of our posts contain affiliate links. By booking from these, you help us to keep Yo soy Mallorca alive and to continue offering the best information about the island. There is no extra cost for you and you can even benefit from some discounts.

Nos interesa tu opinión

Your email address will not be published. Required fields are marked *

  He leído y acepto la política de privacidad

Table of contents

* During the winter season not all hotels and accommodation in Mallorca are open. Because of this, they may not appear on the map.