This charming concertina book follows the journey of a little submersible on a voyage beneath the waves, down into the deep dark ocean and back again. Folding out to nearly 2.5 metres, children can look at all the different things the sub sees on its way, as it travels past a shipwreck, through a coral reef, near to a pod of orcas hunting for their lunch, close to a leatherback turtle feasting on jellyfish, and past some rather strange deep-sea fish. Playful text guides the journey, providing a fun shared experience and a conversation starter for parents and young children.

The reverse side of the concertina features spot illustrations picked out from the main scene, with more expansive information about submarines, ocean life and the dangers it is facing.