Tranquil
adjective
(of a body of water) free from disturbance by heavy waves
“a ribbon of sand between the angry sea and the placid bay”
Similar: placid, quiet, still, smooth, unruffled
adjective
not agitated; without losing self-possession
“spoke in a calm voice”
Similar: calm, unagitated, serene
Word family
tranquilness · tranquility · tranquilly