The dream about the lake could have several meanings depending on the circumstances and the state of the lake. The lake that is crystal clear and you see swimming yourself in it, indicates your ability to move through life with grace and beauty. If the lake is muddy and dirty, it shows that the circumstances are very unfavorable to you. The lake could also be interpreted as the symbol of freedom, especially if you are floating in one. If you are drowning in the lake, you feel helpless in some situation which scares you a lot. The waves of the lake indicates the chaos and turbulence in your waking life.
Read more about dreaming of Lake in other dream meanings interpretations.