Tragic news ... Micky Geller -- a waterskiing star who helped the Univ. of Louisiana-Lafayette win a national championship last year -- has died at just 18 years old.
A cause of death was not revealed ... but according to Geller's loved ones, the Ragin Cajuns athlete passed away suddenly and unexpectedly on May 6.
"With his full throttle approach to life, Micky experienced more in his 18 years than many ever will," his family and friends wrote in Geller's obituary. "However, he was just cracking the surface of the possibilities that lay ahead.