At the shoreline, just underneath the waves. On the beach, because it washed ashore. On a tiny uninhabited island "in the sea". On the salt flats, because th

At the shoreline, just underneath the waves. On the beach, because it washed ashore. On a tiny uninhabited island "in the sea". On the salt flats, because the whole ocean dried up (only applicable for Dead Sea or Aral Sea).