In the waters of the Caribbean, The Dive Detectives find a "ghost ship", an unidentified modern cargo ship. Who is she and why is she unclaimed?

The Dive Detectives search for two missing WWII US subs that disappeared in 1944.

On an island in the South Pacific and in its surrounding waters, the Dive Detectives search for pieces of unused American atom bombs.

Olly and Beth set out to retrieve a downed satellite but Dirk beats them to it. Meanwhile, because of their love for old sci-fi movies, Skid, Brandt and Bobsie are convinced that the satellite has returned to Earth with more than just scientific information aboard.

The subs help a pod of Baltic Sea grey seals find a new iceberg home… but then they can’t get rid of the grateful seals, who follow them around disrupting their work!

With Sub D coming, Beth works hard to clean up and breaks her nose light in the process. She’s forced to wear a huge replacement nose instead.

The subs join Dr. Kate at the opening of the Shanghai Marine Museum. Skid joins them, but soon feels left out as Walter and the subs reminisce together.

Olly and Skid play a prank on Beth, fooling her into believing there’s a live Plesiosaur in a cave. But the prank backfires when Olly and Skid get the fright, and Beth spots a rare ‘living fossil’.

Olly wants to prove to Dr. Daniel what a great research sub he is by finding a special artifact for her in the Mediterranean Sea. Only Olly hasn’t yet learned the proper way to retrieve artifacts – and he almost ruins it!

When Brandt gets caught as ‘bycatch’ in a lobster trap and stranded on a boat everyone tries as hard as they can to rescue him. But finally it’s Brandt’s former rival, Bobsie, who succeeds at the job.