Marcus, the new curator, attempts a high-risk move for a problem shark to the top of the aquarium. Andrew builds a cave for a reclusive lobster, and star attraction Friday the turtle suffers a nasty bite from a mystery tankmate.

Catching rays is a challenge with a sting in the tail. Xav has to find a way to keep Friday the Turtle out of trouble. Freyja gives some care home residents a moving close encounter with sharks.

Marcus and Emma head to the Maldives on a rescue mission for an injured turtle. Back in Plymouth, Ian trains Zeus the zebra shark using a toy boat, and Andrew collects fresh seaweed for Larry the lobster.

Ian has to carry out repairs ten metres underwater in the deepest tank in Britain, and there’s a surprise for volunteer Jill, the aquarium's 86-year-old 'ray whisperer'.

Marcus installs a shark cage to allow visitors a close encounter, and a new octopus arrives from Portugal. Amelia has problems that threaten an ambitious project to replant the seagrass meadows.

There’s a surprise visit from the Princess of Wales, concern for a recent arrival, and a pregnancy test for Florence the shark.