Similar:
* Calm
* Peaceful
* Serene
* Still
* Quiet
* Placid
* Unruffled
* Undisturbed
More nuanced:
* Relaxing: Implies a sense of comfort and ease.
* Soothing: Suggests a calming and restorative effect.
* Peaceful: Emphasizes a sense of harmony and freedom from disturbance.
* Serene: Conveys a sense of deep calmness and tranquility.
* Equanimous: Highlights a state of mental calmness and composure.
* Reposeful: Implies a state of rest and relaxation.
* Idyllic: Refers to a perfect and peaceful setting or scene.
* Halcyon: Indicates a period of peace and happiness.
* Zen-like: Suggests a state of deep meditation and mindfulness.
The best synonym to use will depend on the specific context and the intended meaning.