Mermaids and Sirens are both mythical beautiful female creatures, however they differ in their appearances. A mermaid is a half-woman, half-fish mythical creature; while a siren is a half-woman, half-bird type of creature. The story of both is that they attract the sea sailors and navigators with their alluring and fascinating nature. A mermaids origin is found in the folklore of many different cultures, whereas a sirens origin is found in Greek mythology. This show combines the features of the mermaid with the feature of a siren.
The first several episodes of the show feature establishing shots along the coast with a very red sun and smoke filled sky. These scenes would have been shot during July and August of 2017, when wildfire smoke from the B.C. Interior drifted southwest to the Lower Mainland/Washington state area.
Sibongile Mlambo has described the mermaids in this series: "We are not 'evil mermaids'. We're predators. Like, if you happen to be in their territory and they happen to be hunting in the water, you'll be hunted."
Eline Powell performed the theme song ("Call of the Siren") during San Diego Comic Con 2018, which led to many fans thinking she really sang it in the series. The theme and all mermaid sound effects are actually performed by Mariana Berreto whose voice is also electronically altered to double for Donna's voice.