1. Normally, Shirahoshi measures in at 17m (55'9"). For comparison, that means she's the same size as a middle-of-the-road megalodon.
2. In Atlantis, she's been shrunk down to 30' in length, making her the size of a large male orca. Because of the size change, humans seem nearly twice the size she's used to.
3. She is a smelt-whiting mermaid. Ironically, that species of fish only grows to about 7-8" in length.
4. When she was six years old, she received her first marriage proposal. From an adult.
5. And because she wouldn't marry him, he spent the next ten years throwing axes and other weapons at her. King Neptune, her father, ended up locking her in a tower for the next ten years of her life to protect her from him. This is where Shirahoshi's naivety comes from: Not seeing much of the outside world.
6. The merfolk and fishmen have had bad experiences with humans; the sea-folk tended to be kidnapped and then auctioned as slaves, and the world government didn't bat an eye over it.
7. Shirahoshi's mother was the driving force behind getting Fishman Island recognized in the eyes of the world government, and preached to her people about the importance of accepting humans so as to not further the animosity between their races. Shirahoshi took her mother's words to heart.
8. She is currently the only mermaid able to speak with Sea Kings, which are one of the creatures in the ocean even bigger than she. Some of them are really freaking huge (yes, that's a full-sized ship on the big one's nose), but they will listen to her without fail.
9. Because of that, she is labeled as Poseidon, which is the term for one of the ancient weapons powerful enough to destroy the world.
10. Thankfully, she is far too gentle of a soul to even begin to consider using violence.