Won't the boat staff find it off that someone is missing when they go home? She should be arrested for murder.
Also won't the book be damaged by the water? I thought she would put it in a sleeve or something at least. And she didn't even tie something heavy to it.
Also the brother came just in time, if he just scuba dives a bit in this area he might find it since she just threw it.
Can someone please translate the last chapter? ;-;