Without any intention to initiate a discusion about this matter, "Fortress" in Spanish is a "Fortaleza" it can also be used as "Fuerte" "Fort", "Penitenciary" means "Penitenciaría"; place where the sentences of the inmates are served, you can also say a "Presidio" which is merely a synonymous .

"Presidio" also is often used to mean "Fortress." For example, the Presidio of San Francisco, a famous landmark, was established in the 18th century as a military fortification at San Francisco Bay by the government of New Spain, and continued in use as a military base for over two centuries, but was never a prison.

See:
https://en.wikipedia.org/wiki/Presidio_of_San_Francisco

In Italian (rather than Spanish) it means garrison, defence, aid or protection.

What a strange name for this ship, "Presidio" means "Penitentiary" in English. This is not an appropriate name for a ship.

Regards

Tomi.