Pirana 3D (2010)

A geological failure on the bottom of Lake Victoria opens a breach and releases prehistoric flesh-eaters piranhas. Meanwhile, it is the Lake Victoria spring party where teenagers arrive in to drink beer and booze, get sun tanning, swim in the lake and have sex. When the local Sheriff Julie Forester and her Deputy Fallon discover how danger the lake is, they unsuccessfully try to avoid the tourists to jump into the water to protect them. After saving many teenagers, Sheriff Forester learns that her family is trapped in a yacht that is stranded in the reef and heads in a boat with an acquaintance to rescue her children and family.