I'm almost certain Aliens exist & I actually believe Mermaids exist but not how most people would think. I saw a documentary once over how Mermaids were primates that adapted & evolved in the ocean, & not on land like humans did from primates. They discovered artifacts & weapons similar to arrows that had to have been made by a highly intelligent creature living in the ocean. It's a very interesting documentary & it even stated that humans have only actually discover 10% of the entire ocean, so who knows what's all under there that hasn't been discovered yet? 

UPDATE: Turns out the documentary was fake. 😒