Sereno del Mar (Spanish for "Serene of the Sea") is a census-designated place (CDP) in Sonoma County, California.

[2] The 2020 United States census reported Sereno del Mar's population was 107.

According to the United States Census Bureau, the CDP covers an area of 0.7 square miles (1.9 km2), all of it land.

The 2010 United States Census[3] reported that Sereno del Mar had a population of 126.

There were 115 housing units at an average density of 156.0 per square mile (60.2/km2), of which 85.7% were owner-occupied and 14.3% were occupied by renters.