Here are some synonyms for serenely:
* Tranquilly
* Peacefully
* Calmly
* Quietly
* Composedly
* Unruffled
* Serene
Examples:
* "The sun set serenely over the horizon."
* "She faced her fears serenely."
* "The music played serenely in the background."
Essentially, "serenely" describes a state of being or an action that is characterized by a deep sense of peace and stillness.