Valentine the Mermaid

I needed to draw something in a realistic style for some job application, and I decided to have fun with a very classic subject: Mermaids!

Since it was supposed to be realistic, I wanted to push the concept as far as can be, and got inspiration from documentaries. What would a realistic aquatic mermaid would be like? So I focussed on what is needed for a humanoid to live under water. I observed other mammal species and tried to imagine how those humans would have evolved to survive in the oceans.

According to legends, mermaids provoked shipwrecks to eat sailors. And had to survive in all types of oceans. So what a mermaid needs to survive was (in my opinion)
-gorgeous features, obviously,
-fat. surviving in one digit temperature water requires a good layer of it. Most of aquatic mammals are profusely equipped with it.
-agility in water. I initially went for whale like tail but I decided seal tail would feel more easy to move and give a more agile feel to the creature.