Blackrock Depths (aka Blackrock Deeps) is the deepest part of Blackrock Mountain, ruled by the Dark Iron dwarves who are led by Emperor Dagran Thaurissan. Several minions of the Firelord Ragnaros also make their home in these lava-lined depths. Blackrock Depths is currently the largest 5-man instance in the game, and is likely to remain so, making it a true wonder of the World of Warcraft. The average time to complete the entire instance is 4–6 hours due to its complexity: a large amount of mobs and bosses, several scripts, and many quests. The enemy level range is 48-56, and the minimum level requirement to enter is level 40.

Although the minimum requirement is level 40, it generally isn't a good idea to enter BRD before around level 53, since a player's pull circle will likely be too wide for the mobs within the instance.

The Anvilrage Military are not to be underestimated either, particularly the Officers (who have Divine Shield) and the Medics who can heal their troops. Even for a lesser-geared level 70, they can be dangerous in large groups.

BRD is not visited as often these days as it used to be, since most players choose to level to 58 as fast as possible, and then go to Outland. The rewards for Outland's initial quests also render any of BRD's gear obsolete, so the drops here are probably only going to be of interest to level 49 twinks. Farming for Fiery Weapon enchanting recpe may still be useful, since it commonly used with low level twinks. In Wrath of the Lich King, Blackrock Depths has attracted more interest, mainly because of the instance clearing achievement. Also, surprisingly schematic for Field Repair Bot 74A is wanted, since the famous 4th generation repair bot Jeeves requires 2 of them. Because there are very few people who have played World Of Warcraft before Burning Crusade, this schematic is rare. Even fewer even know where to get it, and finally, almost all players have changed their engineering professions, thus making engineers who can create the bot extremely rare.

The instance is also almost entirely soloable (for Rogues or Hunters, at least, and probably most melee classes) by about tier 5 (level 70), although it is not economically efficient to do so. Although there is money to be made here (especially for miners), the sheer size of the instance and the comparatively low level of the mobs mean that there are better instances for farming (notably Scholomance). For level 80, this instance is very easily soloable. Fire mages may still have harder time than Warriors with Bladestorm,for example.

Although it is not especially profitable, BRD (and the rest of the Blackrock Mountain complex) is well worth at least one visit. These instances represented the original game's endgame content, and were made with a high level of quality.