Salt, lagoons and birds.

A shallow sea turned to salt

The north of Formentera is a low platform of sand, mud and shallow salt water, held between the open sea and the body of the island. The whole strip, from the salt pans of Ibiza down through the Formentera flats to Ses Illetes and the Espalmador islet, forms the Ses Salines Natural Park, declared in 2001. It is also a Ramsar wetland, listed for the birds that use it and for the shallow water itself. Nothing here is high: the land barely lifts above the tide line.

The park is not a reserve set apart from daily life. La Savina, the port where the ferries dock, sits at its edge, and the salt is still harvested. What makes the place unusual is the shallowness: a wide, sheltered shelf of water that the sun can warm and the wind can dry off the flats. That combination of flat land, thin water and steady evaporation is the whole basis of salt making.

Two lagoons and their names

Behind La Savina lie two lagoons of very different character. Estany des Peix is the smaller, a nearly enclosed inlet with a narrow mouth to the sea, so its water stays clear and its bed is mostly sand. Estany Pudent is larger and shallower, lying behind the port and the dunes, cut off from the open sea except through narrow channels that have been dug and kept open. In summer it concentrates into brine.

The name Pudent is usually explained by the smell. In the heat of late summer, when the water drops and the algae and brine shrimp die back, the lagoon gives off a heavy, sour air, and the people who worked the salt did not need a map to find it. The name is not a complaint so much as a description of what evaporation does to shallow water. Brine shrimp and the algae they feed on are the base of everything that follows.

How the salt was worked

Salt making is a form of farming that depends on weather. Seawater is let into shallow basins, called salinas, through wooden gates. Sun and wind do the rest, driving off the water until the salt crystallises on the bottom. Workers then rake it into ridges and heaps, and cart it away dry. On the Formentera flats the basins, low walls and channels are still legible in the ground if you look for them.

Salt has been worked on these flats for centuries, and the trade is older than any of the walls and towers that now stand around the coast. Salt was one of the reasons ships called at the Pitiusas at all, and the pans kept working through periods when the island's population was small and the fishing thin. It is one of the few old industries here that has not turned into a story for visitors: the salt is still raked, still dried, still taken off the island.

Salt was one of the reasons ships called at the Pitiusas at all.

The birds that use the flats

The lagoons sit on a migration line between Africa and Europe, and for a bird flying at night a shallow, food-rich lagoon is an obvious place to drop. Estany Pudent in particular holds water when the surrounding land is dry, so it acts as a refuge in autumn and a staging point in spring. What you see depends entirely on the month, the water level and how much salt is in it.

Birds here divide by what they eat and how deep they can wade. Flamingos, when they come, filter tiny invertebrates from the saltiest water; stilts and sandpipers work the muddy margins; gulls and terns take the open water and the sand spits. Because the lagoon is small, the whole population shifts from one corner to another within a day as the wind and the water move. A telescope helps, but patience does more.

The best viewing is from the landward bank, where a track runs between the water and the low scrub. Morning is usually better than afternoon, because the wind tends to rise later and the birds feed in the calm. In autumn, after the first rains, the lagoon fills and the numbers jump; by late spring many birds have moved on and the flats look empty again. Nothing about that timetable is fixed, which is why local birders watch the water rather than the calendar.

• WadersStilts, sandpipers and plovers work the muddy edges, mostly on passage and through the winter.
• Gulls and ternsLook over the open water and the sand spits, especially in the first hours after dawn.
• FlamingosThey appear in some years rather than every year, most often on Estany Pudent in autumn.
• WaterfowlDucks and grebes gather in the quieter months, when rain dilutes the brine and the lagoon softens.

Water is the whole story

Everything in the lagoons follows the water. Autumn rain dilutes Estany Pudent and the flats turn brackish; through spring and summer evaporation takes the water back towards brine, and the edges dry into white crusts. The salt works depend on that rhythm, and so do the birds. A lagoon that is too fresh supports one set of insects, a lagoon that is too salty supports very few. The interesting weeks are the ones in between.

For a visitor this means the same place can look ordinary in one month and busy with life in another. A morning in May, after rain, brings different birds from a hot afternoon in August, and the smell changes too. Walking the same path twice in a week is worth it: the water moves, the wind shifts, and the birds reorganise around it. Nothing about the lagoon is fixed, and that is the interest of it.

Walking and cycling the shore

The lagoons are easy to reach on foot from La Savina and from Sant Francesc Xavier, and the signposted green routes, the circuits verds, link them with the beaches and the interior lanes. Cycling is the natural way to cover the ground: the island is flat, the distances are short, and the paths that run between the salt pans and the dunes stay quiet for most of the year. Outside the busiest weeks of July and August you may see no one at all.

Go early. The light is low, the wind is usually lighter, and the birds are feeding rather than resting. Late afternoon works too, and in summer it is cooler. Bring water, since shade is scarce around the salt flats, and keep to the edges of the pans rather than cutting across them. A short walk along the margin often shows more than a long one. The ground is flat and sandy, so ordinary shoes are enough in dry weather.

• Green routesThe signed circuits verds cross the island for walking and cycling; the Consell de Formentera publishes the current map.
• On footLa Savina and Sant Francesc Xavier are both short walks from the lagoon margins.
• By bikeThe ground is flat and the lanes stay quiet outside the busiest summer weeks.
• TimingEarly morning and late afternoon are cooler, calmer and better for watching birds.

Salt, posidonia and clear water

The park protects more than the flats. Offshore, the meadows of Posidonia oceanica, a seagrass found only in the Mediterranean, hold the sand in place and keep the water clear. The clarity that lets you see the bottom at Ses Illetes has a second effect: the water stays poor in nutrients, and that is what the salt works and the bird life need. Clear water is not decoration here. It is the working condition.

Anchoring over the meadows is regulated by a Balearic decree, and mooring buoys are installed in some bays in summer. The two halves of the park are easier to understand together: shallow, still, nutrient-poor water over seagrass is what keeps the sand white and the salt clean. Lose the meadows and the beaches thin, the lagoons silt, and the birds find somewhere else. The Espalmador islet and the sandbanks off Ses Illetes belong to the same system, and the meadows between them are why the water looks the way it does.

Visiting without disturbing

Access is the practical question. In high season the Consell de Formentera caps the number of visitor vehicles on the island, and the park has its own rules on where you can drive, park and stop. The lagoons themselves are reached on foot or by bike from the nearby lanes. Signs at the entrances set out what is allowed; the natural park office can confirm anything that is unclear. None of this is complicated, but the rules are enforced and change with the season.

Around the water, distance is the courtesy that matters. Birds flush when something crosses the margin, and a flushed flock spends energy it may need later. Many of the birds that use the flats are on passage, feeding hard before a long flight north or south, and a single disturbance can cost them a day. Stay on the landward side, keep voices low, keep dogs away entirely, and use binoculars rather than your feet to get closer. The lagoon will show you more if you let it come to you.

• Vehicle limitsIn high season the Consell de Formentera caps visitor vehicles; check before bringing or hiring a car.
• Park rulesSigns at the entrances set out what is allowed, and the natural park office can confirm the rest.
• BinocularsA pair keeps you at the edge of the water instead of in it.
• Out of seasonMany businesses close roughly from November to April, though the paths and the lagoons stay open.