Zombi 2, directed by Lucio Fulci, (and titled Zombie in America) isn’t really a sequel to anything, but was marketed in Italy as a semi-sequel to George Romero‘s Dawn of the Dead (which was titled Zombi in Italy). Beyond spectacular zombie effects, the two actually have very little in common.
In this film we follow a young woman, who goes to help out her dad who is sick and lives on a tropical island. Upon arriving at the island she finds out some magical shit has hit the fan and the dead are being raised from their graves.
If anything, the Shark vs. Zombie scene in this movie is worth the watch alone.