Is it Children of the Night maybe?
One of the user reviews at Amazon says the following:
Set in a small town called Allburg, two girls Lucy (Dolenz) and Cindy (Maya McLaughlin) visit an old abandoned church. A creepy looking old gothic cathedral. The legend goes that you can actuall swim in an old crypt beneath the church so the girls give it a try. Well, Cindy loses her crucifix as it floats to the bottom of the crypt and awakens a vampire from his sleep and he immediately kills her while Lucy escapes.