The Costa Rican beach where Malcolm-Jamal Warner tragically drowned was clearly marked with bold warning signs about rip currents and high drowning risks ... TMZ has learned.

Malcolm-Jamal Warner was beloved to television audiences for decades, starting as a teen on The Cosby Show, where he played Bill Cosby's only son, Theo Huxtable.Thus, his death has hit a lot of people hard.

He was declared dead at the scene. The body was sent to the Judicial Morgue in San Joaquín de Flores, Heredia for an autopsy. 10:53 AM PT -- Warner died of asphyxia after he was caught by a high current in the ocean,

The OIJ is providing new details that clarify the timeline of events that lead to Malcolm-Jamal Warner's death. "It was at that moment that they were swept away by the current, and the friend managed to get out,