Primeval - Season 5 - Eps 2: The Submarine
When a Navy submarine in the North Sea discovers a giant underwater Anomaly, Matt, Connor and Abby join the Navy crew aboard, but things go awry when the submarine is pulled through the Anomaly into a prehistoric sea inhabited by giant pliosaurs. The team subsequently attempt to get the submarine back through the Anomaly to their time, while Lester struggles to stop an Admiral from nuking the Anomaly and potentially altering history.
About Primeval

Title: Primeval
First Air Date: 2007-02-10
Last Air Date: 2011-06-26
Status: Ended
Rating: 7.435/10 (from 314 votes)
Language: EN
Seasons: 6
Total Episodes: 36
Network: ITV1 U&W
Genres: Sci-Fi & Fantasy, Action & Adventure, Drama
Production Companies: Impossible Pictures, ITV Productions, M6 Films, ProSiebenSat1 Produktion, BBC America
Synopsis
When strange anomalies start to appear all over England, Professor Cutter and his team must track down and capture all sorts of dangerous prehistoric creatures from Earth's distant past and near future.
Cast

Ciarán McMenamin
Matt Anderson

Ben Mansfield
Hilary Becker

Andrew-Lee Potts
Connor Temple

Hannah Spearritt
Abby Maitland

Alexander Siddig
Philip Burton

Ruth Kearney
Jess Parker

Janice Byrne
April Leonard

Ruth Bradley
Emily Merchant

Ben Miller
James Lester