It is eventually revealed that an evil company was conducting illegal biological weapon experiments under the guise of "de-aging serum". When their ship sank, the chemicals leaked, reanimating corpses on the seabed.

"Ola de zombis: Marea de muerte"

However, I can offer you useful, legal information about the film:

The most telling aspect of the query is the inclusion of the terms "Cuevana" and "Pelisflix." These are not standard, legitimate streaming services like Netflix, Amazon Prime, or HBO Max. Instead, they represent a massive, gray-market sector of internet piracy that is particularly prevalent in Latin America and Spain.

Espero que esta información te sea útil. ¡Disfruta la película!