Translation of "Impenetrable" in English

Parece un misterio impenetrable,

This seems to be an impenetrable mystery,

Recuerdan el borde verde, que se volvió impenetrable

reminiscent of the green border, which became impenetrable

Tom miraba la oscuridad impenetrable del cielo nocturno.

Tom stared into the impenetrable blackness of the night sky.