I think that there are creatures out there that are unknown to us, but I'm not so sure about mermaids. I think of them more as mythical creatures, like the minotaur. What about you?
I think that if they exist, because if they investigate it, it is because they have found something
I have seen so-called footage of mermaids and corpses of them, but I'm skeptical. Are mermaids the only cryptid you feel are real, or do you feel that way about others, such as bigfoot or chupacabras?
no, I don't believe in those things, but as I said, if that's what people talk about, it's because it was ever seen.
There is a good point to be made: 95% of the ocean is unexplored. Mermaids and other creatures could be out there, away from our prying eyes.
you are right in what you say, perhaps there are many things that we still do not know.
There have been sighting of mermaids even in the 1600s. I wish that there were more documented sightings in recent times, as people always have cameras on them with their phones.
perhaps they are not creatures worth investigating.
All of the evidence of them that I've seen has been debunked, so I would think that cryptids such as bigfoot have a higher likelihood of existing. 
yes, of course .. you are right. you have a fairly extensive vocabulary.