This weekend we've been to Slanic Prahova and I actually swam for the first time in the salty lake. A weird sensation, since this high concentration of salt in the water just pushes you to the surface, so all you can do is use your hands - your feet will just float above the water :).
Some people found some other kind of fun, floating on a wooden platform,
and sometimes trying to sink it... without any results of course :).
PS: the maximum depth of this lake is 15 m!