'Podcam' shows life of dolphins in BBC Spy in the Pod series
Film-makers have infiltrated the ocean with secret cameras to capture dolphin behaviour in the wild as it has never been seen before.
They enlisted a menagerie of creatures, such as a molluscs, sea turtle and squid, with hidden lenses to get up close and personal for a new BBC natural history programme.
The series director John Downer and producer Rob Pilley spoke to BBC Breakfast.
Dolphins - Spy in the Pod begins on January 2 on BBC One at 8pm.