Lake Retba in Senegal is the world's second most saline body of water, thanks to being cutoff from the ocean some 50 years ago.
Workers produce 60000 tons of salt per year by harvesting it from the lake bottom and sun-drying it before adding iodine and filling it into bags for sale.
"How 60,000 Metric Tons of Salt Are Harvested from One of the World’s Saltiest Lakes", by Eater
For comparison, the world annual salt production (not only from lakes or oceans), is around 280 million tons. The oceans contain a virtually inexhaustible supply of salt.