General Antonyms:
* Turbulence: This is a good general antonym, suggesting chaos and unrest.
* Disquiet: This implies a state of unease or worry.
* Agitation: This suggests a state of being restless and disturbed.
* Chaos: This implies a complete lack of order and control.
* Stress: This suggests a state of mental or emotional strain.
More Specific Antonyms:
* Noise: This is a good antonym if you are referring to a lack of peace and quiet.
* Conflict: This is a good antonym if you are referring to a lack of harmony.
* Disturbance: This is a good antonym if you are referring to something that disrupts peace.
* Motion: This is a good antonym if you are referring to a lack of stillness.
The best antonym for tranquility will depend on the specific context of the sentence.