At average speed, one can do about 50 trips to the nature altar via the Abyss per hour, using the amulet of glory to teleport back to Edgeville, and using an equipped pickaxe to mine through the rocks in the Abyss. You need to recharge your pouches every nine trips, at the Dark mage, to prevent the giant pouch from degrading.
Using the small through giantRunecrafting pouches, you can hold up to 54 essence per trip, resulting in a profit of 22,140 coins per trip (ignoring other expenses). This assumes at least level 91 Runecrafting – without making two nature runes per essence, this is not as good a money making method.
The Mage of Zamorak is located low-level Wilderness, near the source of the River Lum. This is a fairly safe area, but there might be player killers, so it is advised not to take expensive items on the trips to the Abyss. The best setup would be cheap but protective gear (e.g. dragonhides). Use of weight-reducing clothing and abyssal bracelets is also recommended. Falador shield can be useful to negate the loss when killed by a player, as it can recharge prayer instantly (once or twice per day) which can be used to activate Protect Item. Inside the Abyss, the creatures there will be aggressive and might do fair amounts of damage. See Abyss#Inside the Abyss for more information on how to navigate the Abyss. Once inside, enter the nature rift and craft the essence in your inventory and your pouches. Teleport back to Edgeville with an amulet of glory and repeat.
Assuming all pure essence is bought on the Grand Exchange for 6 coins each, you can make approximately 1,107,000 coins per hour using this method (ignoring other expenses).
Due to constantly changing prices on the Grand Exchange, some information in this article may or may not be current. It is strongly recommended to check the live prices on the Grand Exchange before making large investments in any method. All prices on this page are cached, meaning it is possible that they appear out of date. To force a new cache of this page, click this link. If a money making method is out of date, you can edit it or leave a message on the talk page.