"Precambrian (Avatar Creation)" sounds very playful.
The bongos rhythm in "Shallows(Epipelagic)" is nice and I like the synth lead and pan flute melodies. The high pads and bells add a nice soft texture.
In "Ectosymbiosis (Mesopelagic)", the pads and buzzes give the song a nice electric vibe, while the chimes and bells keep it playful. Nice bass melody at 1:45
"Biolumenesca (Abyssopelagic)" is very laid back, though the dissonance adds some tension.
"Deepest Known (Hadopelagic)" obviously nails the creepy vibe at the start, though starts to get a bit playful as the bass followed by the mallets come in. Very nice and effective.
"Wash Away (Closure) (Rediscovered)" works as an ending/credits song.