Lake Retba, the pink lake

Real algae, real salt, and three thousand people working it by hand

Check what colour it is before you go. Extreme flooding in September 2022 contaminated Lake Retba and turned its famous water green, and by 2025 it had regained only some of its colour.

That is not a cosmetic problem. The lake sits 35 kilometres northeast of Dakar, separated from the Atlantic by nothing more than a corridor of dunes, and its pink comes from Dunaliella salina, an alga that manufactures a red pigment to help it absorb sunlight in water carrying up to 40 per cent salt. The same salinity supports a harvesting industry, and thousands of people depend on it. When the floods came, one salt farmer told reporters he had raked in what he feared was his last harvest. The colour and the livelihood come from the same chemistry, so losing one threatens the other.

In normal years the pink is strongest from late January to early March, in the dry season, when evaporation drives the salinity back up. Lac Rose, the French name everyone uses, means exactly what it says.

The salt is the industry the colour sits on top of. Up to 3,000 collectors, men and women from across west Africa, work the lake six or seven hours a day and take out something like 38,000 tonnes a year, most of it going to Senegalese fishermen to preserve fish for dishes including thieboudienne, the national dish of fish and rice. They coat their skin in shea butter first, because the brine does real damage otherwise. The water is salty enough to float in, like the Dead Sea.

The lake was under consideration by UNESCO as a World Heritage site as of 2026, which is a slower process than a flood.

There is a wider lesson in it for anyone planning a trip around a natural spectacle. A place can be famous for one thing and stop doing that thing without the guidebooks noticing for years. Lake Retba is recovering, but a photograph taken in 2019 is not a promise about next month.