Keeping up with conspiracy theories, this is quite interesting. Allegedly someone found evidence of a mer-creature that was humanoid. There have been documented cases of sailors actually netting these creatures. They never caught one but there are some who have seen them. To me, it's quite possible...the ocean is a very big place and we have not really come close to exploring it all.
The people in this documentary are of course actors, to protect the people that were involved.