waves - Why can we hear sound better on the water than on land?

If we sit in a boat on a lake we can often hear people talking on the shore clearly in contrast to sitting in an empty field and hearing the people talk over the same distance.

I heard that this effect comes due to temperature differences of the air over land and over water and that the sound waves bend somehow resulting in amplifying the sound. But I do not really understand how or why we hear the sound better.

Does anyone know the correct/detailed physical explanation for this?