@Tony Page are you familiar with this book? https://www.amazon.com/Invisible-Residents-Reality-Underwater-UFOs/dp/1931882207 I was a big fan of Mr. Sanderson when I was young.
Don, Thanks for the information.No I haven't read it but it is interesting and right in line with the type of book I read. Many years ago I Belonged to a book club similar to book of the month club, except it was for paranormal, Cryptids, UFO's etc. I had a nice size collection of these type of books, I lost them in the house fire we had. I will look into that book.
A quick note, I ordered the book from thrift books, I got the hardcover version for $11.09. I also picked up a book for my Grandson, plus got free shipping. Now I'm looking forward to reading it.