Sure, you’ll be heading around the underground pass several times anyway for the quests in that area, so feel free to explore. Just know that death in the past during the quest will force you to backtrack a bit, so it might be worthwhile to come back and see all the secrets of the past whenever you aren’t part of any quest. There’s a lot to do and see, especially since you are exploring one of the largest areas in Runescape! Take it all in, have fun, and be patient with it all. It can get frustrating with all the powerful enemies, and in some cases, the largest level of the cavern has taken an hour or so to clear. Just take your time and don’t get too discouraged.