Dua of Yunus — in extreme distress
لا إلهَ إلاّ أنْـتَ سُـبْحانَكَ إِنِّي...
لا إلهَ إلاّ أنْـتَ سُـبْحانَكَ إِنِّي كُنْـتُ مِنَ الظّـالِميـن
La ilaha illa ant, subhanaka innee kuntu minatth-thalimeen
Translation
None has the right to be worshipped except You, how perfect You are, verily I was among the wrongdoers.
When to recite
The dua of Prophet Yunus (Jonah) recited from inside the whale. The Prophet said no Muslim recites this in any difficulty except that Allah will relieve him of it.
Source / Reference
At-Tirmithi 5/529