Into the Drowning Deep by Mira Grant
Seven years ago a ship, the Atargatis, sailed to the Mariana Trench looking for mermaids. Imagine Network planned to make a huge amount of money off the planned mockumentary. Instead, the entire crew was lost at sea and only raw video footage to show what happened. They had found mermaids - and mermaids are not friendly.
Now, the entertainment company is planning a second voyage. A film crew and a large group of diverse scientists are going back to find out what happened and to prove mermaids exist. Diverse in disciplines - marine biologists, cetologists, chemical biologists, cryptid hunters, and diverse in backstories - sexual orientations, disabilities, financial resources, and cultural backgrounds. Some of the scientists have personal reasons for going, like Tory whose sister died on the Atargatis and Dr. Toth whose life's work has been centered on Sirens. Others are approaching it as a cruise where they get to do their own research, not believing in the mermaids.
I...