"Down The Hobbit Hole" is an orchestral piece from the Season 6 soundtrack. It plays during the series finale.
At the flash sideways Hospital, Jack greets Juliet Burke. When David arrives, Juliet is revealed to be David's mother and Jack's ex-wife. Since Jack cannot go to the concert, he suggests they bring Claire instead. As Juliet and David leave, they pass Sawyer on the way to the elevator. Sawyer heads through the hospital to find Sun Paik.
On the Island, Locke suggests only he, Desmond, and Jack go further through the bamboo grove. As the three head out, Hurley tells Jack he believes in him. The three continue to walk through the jungle, until they find The Heart of the Island. Once there, Locke and Jack prepare to lower Desmond down. As Jack ties the rope around Desmond, Desmond tells Jack of the flash sideways world, where Desmond believes he soon will go, rendering everything they are doing useless. Desmond offers to find a way to bring Jack there, but Jack rejects it, believing there are no do-overs and that everything they do matters.
Locke, Jack and Desmond then climb into the cave and stare down at the Light below.
The piece begins with Desmond's flash sideways theme, which gives way to Ford and Straume's motif. The next movement begins with a section of the first traveling theme that doesn't play in the episode. The Light theme plays, followed by the Heart theme, then the Light theme again, and then back to the Heart theme. The piece concludes with Desmond's theme and, finally, the Light theme again.
The title references "Down the rabbit hole", a phrase from Alice's Adventures in Wonderland, and "hobbits", characters from Lord of the Rings, whose film adaptation co-starred Dominic Monaghan. During this scene, Desmond prepares to descend into a hole. Like the climax in Lord of the Rings, he enters a lava-filled area to negate the source of the main villain's power.