Leave the sand where it lies.

A park, not a resort

Most of the sand on Formentera lies inside the Ses Salines Natural Park, which covers the south of Ibiza, the north of Formentera and the sea between them. It was declared a natural park in 2001, it is a Ramsar-listed wetland, and salt is still harvested in the lagoons behind the beaches. This is a working landscape with protections attached, not a blank space for the day.

That status shapes what you can do. Paths and boardwalks exist so that feet stay off the dunes. Buoys in some bays exist so that anchors stay off the seagrass. The rules are not aimed at visitors in particular; they apply to everyone on the island, and the natural park office and the Consell de Formentera are the bodies that set and enforce them. Knowing them before you arrive makes for a smoother day.

Stay off the dunes

Behind the north shore beaches there is a low ridge of dunes held together by juniper, mastic and sea daffodil. These plants are what keep the sand in place. A single path worn through them widens with every season until a gap opens and the wind starts moving the beach inland. The wooden walkways at Ses Illetes and Llevant exist for exactly this reason, and they are not decoration.

Where there is no boardwalk, use the established gaps and keep to the firm sand near the water. Do not drag sunbeds, coolers or umbrellas across the vegetation, and do not prop anything against the juniper for shade. Dune plants are shallow-rooted and slow. What looks like a sturdy shrub may be decades old and will not recover from a single season of being sat on, leant against and walked over.

• WalkwaysUse them even for short crossings; the sand beyond the posts is the part that needs protecting.
• JuniperDo not break branches for shade or windbreaks; the shrubs hold the dune together.
• TowelsLay them on open sand, not on vegetation, and shake them out before you leave.
• PathsWhere a boardwalk ends, follow the worn gap rather than making a new one.

Posidonia is not seaweed

The brown, fibrous litter along the tide line is Posidonia oceanica, a flowering seagrass that grows in meadows from the shallows down to about 30-40 m. It is not algae and it is not rubbish. Storms tear leaves loose and the sea pushes them ashore, where they form banks that hold sand, shelter small animals and protect the beach from winter erosion. Those banks are a working part of the beach, not a mess.

Leave them. Do not rake them off, bag them up or clear a neat patch to sit on; move a few metres along the shore instead. Where the natural park or the Consell de Formentera manage the banks, clearing is a decision made with the beach in mind, not with a lounger. Offshore, the same plant is the reason the water reads so clear: the meadows filter it and hold the sand down.

The brown line at the tide edge is the beach's own defence, not litter.

What not to take home

Sand, shells, pebbles, driftwood, posidonia, dune plants and lizards all stay on the island. It is a small thing when one person takes a handful, and a large thing across a summer of ferries. Removing sand and shells is restricted in protected areas, and the natural park office can explain what applies where. The general rule is simpler: if it was on the beach when you arrived, it should still be there when you leave.

The same applies to living things. The Pitiusan wall lizard exists only on Ibiza, Formentera and their islets, and it is not a souvenir. Do not catch one, box one or carry one to another island. Plants, cuttings and seeds travel the other way as well, bringing species that do not belong here. Shake out towels and shoes before boarding the ferry back, and check bags for stowaways.

• SandLeave it below the tide line; a jar of it is a small removal repeated hundreds of times.
• ShellsEmpty shells are habitat and building material; look at them and put them back.
• PebblesStone beaches stay stony because the stones stay; do not build cairns or take one home.
• DriftwoodIt shelters insects and holds sand; leave it where the winter sea left it.

Anchoring and mooring

Anchoring over posidonia meadows is regulated by a Balearic decree, and mooring buoys are installed in some bays in summer. An anchor dragged through a meadow cuts rhizomes that take a very long time to regrow, and the scar stays visible for years. If you arrive by boat, take a buoy where one is available and anchor over sand if not. Never anchor on the dark patches.

Rules and buoy fields change: which bays carry buoys, how many boats are allowed, whether anchoring is restricted in a given season. Check with the natural park office or the Consell de Formentera before you set out, and read the notices at the harbour in La Savina. A charter should brief you, but responsibility stays with whoever is at the helm. The waters around Espalmador are watched closely.

Shade, sunbeds and space

Sunbed concessions operate on parts of Ses Illetes and other beaches in season, and most close roughly from November to April. Where they exist, they occupy a defined strip. Keep the rest of the beach open: do not move the loungers, do not rope off a stretch of sand with towels at dawn, and do not set up in the narrow gap other people need to reach the water.

Umbrellas are useful and also a hazard in the wind. The tramuntana and the sea breeze can lift one across a crowded beach. Weight it properly, take it down when you leave, and do not wedge a pole into the dunes to hold it. On the busiest days at Ses Illetes, the difference between a good afternoon and a hard one is usually a few metres of courtesy and an earlier arrival.

Rubbish, wind and cigarettes

Formentera's bins are emptied often in season, but they still fill. The wind does the rest. Anything light enough to blow away will blow away, and a plastic bag that leaves your hand ends up in the water or wrapped around a juniper. Bring a bag for your own rubbish and carry it to a bin in La Savina, Es Pujols or Sant Francesc rather than stacking it beside a full one.

Cigarette ends are the most common item on the sand and among the worst. Filters are plastic; they do not break down, and the sea does not take them away for good. Dropping one is littering wherever you are. Fruit peel and crumbs are not harmless either: they pull gulls and rats towards the dunes and change how the beach behaves. Pack them out with everything else.

• Take it backPlan to leave with everything you arrived with, including picnic waste and packaging.
• CigarettesCarry a small tin for filters; they are plastic and do not disappear.
• WindWeight down anything light and pick up what escapes before it reaches the water.
• FoodDo not feed gulls or lizards; scraps attract animals that damage the dunes.

Arriving without adding a car

In high season the Consell de Formentera caps the number of visitor vehicles on the island, and parking near the popular beaches fills early. The signposted green routes, the circuits verds, suit walking and cycling, and the island bus network reaches the main beaches in season. Bringing a car is a choice with consequences on an island this size; the alternative is usually a short ride and an easier arrival.

Ses Illetes is the sensible base for a first visit. It is close to La Savina, reachable on foot or by bike along a marked route, and it shows the whole set of rules in one place: boardwalks, buoys, posidonia banks and all. Arrive before mid-morning in July and August, or come in the shoulder months, when the beach is quieter and the places that stay open are the ones that live here.

The rule behind the rules

Every item on this page comes from the same position: Formentera is a small island with a narrow margin, and the things that make it worth the ferry crossing are the things that are easiest to damage. The dunes, the meadows, the lagoons and the lizards are not separate attractions to be visited and left behind. They are the island's structure, and a beach that loses them stops being the beach people came for.

None of it requires much. Walk on the boards, leave the brown leaves where they lie, take your rubbish to a bin, keep the anchor off the dark patches, and put the lizard back on the wall if it climbs onto your hand. Do that and the island carries on doing what it does, which is to look almost untouched in the middle of a Mediterranean summer, for the people who come after you as well.