Giants Mollusks are released from the earth by an earthquake and start killing people.
as Lt. Cmdr. John 'Twill' Twillinger
as Gail MacKenzie
as Dr. Jess Rogers
as Jody Simms
as Dr. Tad Johns
as Lt. Robert 'Clem' Clemens
as Sheriff Josh Peters
as Sandy MacKenzie
as Connie Blake
as Seaman Fred Johnson
as Sally
as George Blake (lab assistant)
as Mrs. Simms
as Lewis Clark Dobbs
as Seaman Wyatt (Radioman)
as Seaman Morty Beatty
as Monster Victim
as Deputy Larry
as Admiral Greenhouse
as Deputy Scotty
as Other Lock Watchman
as Boy with Morty's Cap
as Coroner Nate Brown
as Gatekeeper
as Patterson
as Watchman at Lock 57
as Seaman Howard Sanders
as Davis - Resort Owner
as Captain Masters
as Deputy Brewer
as Clarke
