The Valley of the Giant Oysters was an undersea region on the planet Dac near the Seascape Mountains. As its name implies, the seabed of this region was populated with oversized mollusks, luminescent fauna and varying species of eels as well as the sentient Whaladons.
In 4 ABY, Rebel Alliance forces staged their final assault against Emperor Palpatine's newest superweapon, the Death Star II. At the close of the battle, the space station was destroyed, and several large fragments were shunted throughout the galaxy from the force of the explosion. A large section of the station landed in the seas of Dac and settled down in the Valley of the Giant Oysters. A year later, the self-proclaimed son of Emperor Palpatine, Trioculus, ventured into the Valley on board a Whaladon-hunting submarine in search of the mysterious Glove of Darth Vader. He personally sifted through the wreckage, and recovered the glove. Shortly thereafter, Trioculus fought against Rebel heroes Luke Skywalker, Admiral Ackbar, C-3PO and R2-D2, and succeeded in forcing the Rebels to retreat from the undersea environment.