The passage states that the main reason why the Lake of Köyceğiz has become an important ecological area is that ----.

Travelling east along the coast to Antalya, you may
easily miss the great Lake of Köyceğiz lying behind
the orange trees. Visitors at nearby Dalyan sail
regularly back and forth between the famous small
peninsula of sand where turtles build their nests and
the ancient ruins of Caunus four miles away. They
may even visit the mud baths at the tip of the lake.
Yet they seldom try to swim in the lake itself, which is
strangely hidden away from both the highway and the
tourist crowd; this has helped the lake to evolve into a
rare area of ecological importance.