There are 14 main bodies of water in the lake district but only one official "lake" and that is Bassenthwaite Lake.
All the rest are "meres" or "waters", for example Windermere, and Coniston Water.
Bassenthwaite Lake is the only one actually called a Lake. The others are called Meres, Waters or Tarns. (The Tarns are smaller.)
It is always difficult to define a smallest as it depends on what...