Glee actress Naya Rivera, 33, is missing, feared dead, on a Southern California lake after her young son was found floating around alone on a boat.

Divers were searching for the star after her 4-year-old son was found adrift on the boat, which Rivera had rented about three hours earlier, by another boater on Lake Piru.

According to local media, her son, Josey Hollis Dorsey, told investigators that he and his mother were swimming, but his mother never got back into the boat.

Josey - whose father is Naya's ex-husband Ryan Dorsey - was reportedly asleep when he was found in the rented vessel by another boater. Sources also told TMZ Josey told authorities that his mother had "jumped into the water but didn't come back up."

A Ventura County Sheriff's Department confirmed they had deployed air and dive teams to "search for [a] possible drowning victim".

Rivera's life jacket was still in the boat and her vehicle, a black Mercedes G Wagon, was later found in the car park with her purse inside.

Divers immediately started searching the lake, but so far there's no sign of the Glee star, and the search has been called off for the night and will continue tomorrow.

Josey is said to be okay and is with family members.

The actress recently posted a message on her social media accounts, eerily writing that "tomorrow is not promised" along with a selfie.

"No matter the year, circumstance, or strifes everyday you're alive is a blessing. make the most of today and every day you are given. tomorrow is not promised," the star posted to her 1.5 million followers last Friday.

Rivera also shared a photo of herself kissing Josey on social media, adding the caption: "Just the two of us" on Tuesday.

Rivera was arrested on domestic battery in 2017 against her ex-husband Dorsey after an altercation during which she allegedly hit him at their West Virginia home.

Dorsey claimed that Rivera struck him in the head and face, and hours after the alleged incident, her emotional court appearance was caught on camera for the world to see.

Law enforcement said at the time that alcohol was a factor in the incident.

The charge was dropped after Dorsey told prosecutors he didn't want to proceed.

E! reported that "Naya's friends and family (were) very concerned for her wellbeing" following the explosive incident.

The pair were married in 2014 but finalised their divorce in 2018 and share joint custody of Josey.

Glee has been plagued by controversy, heartbreak and scandal, earning it the title of the "Glee curse".

Glee's leading male Cory Monteith, who played Finn, died of a drug overdose in 2013 at the age of 31.

His co-star, Mark Salling, also another series favourite in the role of Puck, killed himself in January 2018. He was 35.

Salling was awaiting sentencing on child pornography charges at the time of his death.

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