Presented by Fergus Keeling
'It was coming right at us, real fast, with a big wake. It was throwing its head all over the place, and it must have been about 100 feet long - a snake-like dinosaur!'
Eye witnesses from around the world recall their startling encounters with unknown ocean giants. But what are the creatures they have seen?
Can the sightings be explained, or might there still be some surprises in store for those who study life in the sea?
BBC Bristol
(Re-broadcast on New Year's Day at 11.0pm)