The Sunwell was a fount of mystical power at a convergence of powerful ley energies in Quel'Thalas, created by the high elves who used a vial of sacred water stolen from the Well of Eternity.

The well's potent arcane magic fed and strengthened all high elves on Azeroth. Thus, the city of Silvermoon was established. The power of the high elves grew, and they cast an enchantment on the Eversong Woods that would keep them bathed in eternal springtime. Elven magi crafted monolithic Runestones along the borders of Quel'Thalas; these massive stones powered a magical shield intended to mask the elves' magic from extra-dimensional threats and protect the land from invasion. The hard-won peace of Quel'Thalas would endure for roughly four thousand years.

For millennia the mystical pool of energy fueled the potent magic of the exiled high elves. The Sunwell's inexhaustible power permeated the elves and infused them with a constant supply of arcane energy. For generations the high elves protected and cherished the well, benefiting from its powers even when outside the borders of their homeland, Quel'Thalas.

Extremely difficult, even with a full group of level 80's. I never had the pleasure to experience it during BC, but I've been in four times at 80 and have never completed it, never been past the Eredar Twins. Boss mechanics are great, requiring coordination and percision. My hat is off to those who completed this raid during BC.