There are several definitions of a lake, none of which are accepted everywhere as the "right" one. Generally, a lake is larger and deeper than a pond, but exact acreage and depth definitions vary.
It actually depends! For example, most are. Like Lake Ontario and Lake Michigan. But the Great Salt Lake in Utah is apparently the only salt lake in the world.There are many non-fresh water lakes,...
Make sure the health department says the lake is OK to go into first of all. Second if you do go into the lake be sure to wash the piercing out with clean running water after your swim.