That's why I'm posting this advice, they are not common if you count all lakes and all rivers in the world but they are very common in the rivers and lakes near

That's why I'm posting this advice, they are not common if you count all lakes and all rivers in the world but they are very common in the rivers and lakes near where I live for example. That's why most drownings around here happen to immigrants: local people know that it is crazy to go swimming in some places, because they know that something bad happened to a lot of swimmers over the years in those points, but if you don't know that history it is easy to make that possibly fatal mistake.