This is the Great Salt Lake. It is what is left of the prehistoric Lake Bonneville which was much larger. When the earlth's climate warmed, the lake began to evaporate. It is replenished by three tributaries, the the water has nowhere to go since it has no outlets except evaporation. Because of this, the lake has a very high salt content. If you were to go swimming in the lake, you would not sink, because the water is so salty!