Located in the eastern part of Tanaris, the Caverns of Time contain various portals to different key time periods and events in Warcraft history. The caverns act as a crossroads for the various timelines, and through them one can travel back and forth along the ebb and flow of time. The Caverns of Time are home to Nozdormu and the bronze dragonflight. It is their sacred charge to guard the caverns against the intrusion of mortals, whose interference would assuredly disrupt the flow of time.

When implemented as part of the expansion, the caverns will contain three instances and a battleground set in the past. This provides a tremendous opportunity for Blizzard, allowing them to implement diverse and exciting new content; this content could be culled directly from their previous Warcraft games or periods of the Warcraft history that elapsed between them. Currently Blizzard has made public plans to implement four distinct events accessible through the caverns of time.

For a while it was possible to enter a portion of the Caverns through an entrance in Tanaris guarded by Chronalis and several other named dragons. While normally the entrance couldn't be passed, it was possible for a player to get through the gate while dead and revive inside if their corpse was close enough. Before this trick was patched out players who took advantage of it were treated to a glimpse a starry void filled with such odd sights as a small boat full of skeletons floating in space and a enormous hourglass.

Fear? No need - you can get in exactly as the movie shows - if you don't know which one, check google. Anyways, caverns are completely done - no strange textures or glitches. The animation is also completely done (very nice lightshow btw:)). As it seems, the caverns are gonna provide entrance to 3 instances. The areas behind instanced gates look done (as much as i can see, anyway), so i think expansion(Burning Crusade) is very near. i say THINK, 'coz I haven't been to Hyjal myself yet - i only saw a movie and it looks completely done. I just hope Blizzard doesn't realy ban accounts because of these little adventurous trips into the mysteries of WOW:) Anyways, You are going in at your own risk - the area is not marked as UNDER CONSTRUCTION (Hyjal clearly is) - the entrance is only blocked by a big rock (and a deathshead elite dragon called Anachronos:)) It's strange that Blizzard didn't put a wall right behind the entrance (like in Hyjal) - it's like they don't mind ppl going in - and i think they shouldn't. I think these situations bring a more epic feel to the whole game - adventurers, who dare, see things the other don't. My oppinion, anyways:))
Let me stress again :
YOU ARE GOING IN AT YOUR OWN RISK!!

Located in the eastern part of Tanaris, the Caverns of Time is currently a closed portal to three separate instances based upon historical events throughout Warcraft's history. While certain areas of the caverns can be seen today (architecture only), the Burning Crusades expansion is expected to fully open the caverns and all related instances.