Gustav Kobbé discusses this passage as a variation of the “Isolde” or Desire motive.  Only after repeating for the third time does he acknowledge Desolation as representing the vast waste of the empty ocean (Kobbé, p. 130).  Lavignac, on the other hand, refers to Desolation as a continuation of Pain of Death, which he labeled “Solitude” (Lavignac, p. 308).

Motive Labels
“Oed und leer das Meer” or “Vast Solitude of the Ocean” – (Redlich, p. 28)
"Meeröde” or “Deserted Sea” – (Pfohl, p. 227)
“Motiv der Öde (auch des Sehnens)” or “Motive of Desolation” “(also longing)” – (Windsperger, p. 45)
"Death Draught” – (Redlich, p. 23)
“Poison”
"Death”
"Drink of Death"

Desolation – Order of occurrence by Act and Scene
Act III: Prelude, Scenes 1-2