"The Forbidden Forest. The wards don't encompass the whole thing, so if you walk far enough you could get out or come in," Snape said, as if it were obvious. To be fair, Regulus couldn't help but agree. How had it never occurred to Regulus before, in all the many afternoons spent daydreaming up ways to leave the castle? It made so much more sense for the Forest to be off-limits, too, if there was such a flaw in the wards.