with the naked eye
No se puede distinguir a simple vista.
It cannot be distinguished with the naked eye.
Creo que hay más de lo que se ve a simple vista en ese hombre.
I think there's more to that man than meets the eye.
— Paddington 2 (2017)
Las bacterias son invisibles a simple vista.
Bacteria are invisible to the naked eye.
It can be seen with the naked eye.
It was plain to see.
A simple vista, la costa parecía desierta.
At first glance, the coast seemed deserted.
It's in plain sight.
Los átomos no se ven a simple vista.
Atoms cannot be seen with the naked eye.
A simple vista, su red es de alta tecnología.
At first glance, their network is high-tech.