Jazz Icon Ken Peplowski Dies Just Before Cruise Ship Performance

Acclaimed jazz bandleader Ken Peplowski has died ... and his sudden passing occurred right before he was to play on a cruise already at sea, TMZ has learned.

A passenger on The Jazz Cruise tells TMZ ... the renowned clarinetist and saxophonist died yesterday. Ken was supposed to play on the cruise in the late afternoon with a quartet ... and was a no-show. A search ensued and he was found dead inside his cabin. His death was announced prior to the big band main feature concert later that night. The ballroom was shocked ... with a lot of gasps and then silence.

A statement from the niche cruise's executive director, Michael Lazaroff, reads in part ... "He was a great musician, but he was also one of the very best entertainers ever. I do not know any musician who respected the bandstand more than Ken. He was always prepared, love performing with his fellow musicians, and, man, could he play!"

A friend and radio station WBGO's former director of editorial content wrote ... Ken had been "suffering from multiple myeloma" and the jazz icon "battled the often fatal disease with a unique combination of courage, fortitude and humor."

The Jazz Cruise is planning a more extensive remembrance, per Lazaroff.

Ken was 66.