This was an interesting chapter, I think the underwater diving. I think that is would have been better to understand what Mist feels about Siren if their had been more of a comparison with his previous relations, if their was any and would have helped to give more of a back story to his past love life. Still it was a good chapter, I will be looking forward to see more soon of this again.

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What's your chapter scedule?

8308400
I seem to be writing and releasing these at a fairly even schedule of once every 2 to 4 days.

Shipwrecks make me wet.

Report both for this and the previous chapter. I really enjoyed those chapters examining the frigate and the reef, as well as meeting new characters (You do really well on writing Twilight, that I can judge at least from the bits we have seen of her).
I can't say I'd be too fond about where the relationship between Mist and Siren is heading, but I'm not much into romance in general. Anyway, as long as any story has adventure and mysteries to offer, I'll keep reading it
Furthermore, I really liked that ballad part. A possible foreshadowing, maybe?

Addendum1: I think you should check the number of Mist's friends that were saved along him in the previous chapter
Addendum2: The mechanism of "fish' lungs" you describe in this chapter is in fact a diffusion model present in some water insects and turtles. Fish gills function more based on countercurrent exchange. Sometimes my biologist profession is rubbing off of me

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Switched "lungs" for "gills". As for the ballad, it may come in handy later. Or I just like writing poetry and sometimes incorporate it into stories. Who knows.