Alok Jha is a journalist and broadcaster based in London. He is science correspondent for ITN and, before that, was science correspondent at the Guardian.

He has presented science programmes for BBC2 and BBC Radio 4. Alok received a science-writing award from the American Institute of Physics in 2014, was named European Science Writer of the year in 2008, and has been shortlisted for feature writer of the year at the annual Association of British Science Writers awards.

He is the author of How to Live Forever and The Doomsday Handbook, and his latest is The Water Book.

Helen Scales is a marine biologist, freelance researcher and broadcaster. She appears regularly on BBC Radio 4, Sky News and the BBC World Service, and has presented documentaries on topics such as whether people will ever live underwater, the science of making and surfing waves and the intricacies of sharks' minds.

Her doctorate involved searching for giant endangered fish in Borneo; she's also tagged sharks in California, and once spent a year cataloguing all the marine life she could find surrounding a hundred islands in the Andaman Sea. She is the author of a book about seahorses, Poseidon’s Steed, and her latest book is Spirals in Time: The Secret Life and Curious Afterlife of Seashells.