That was a great listen! You're good at keeping the ambience but also including memorable touches that keep the listener emotionally invested without being too in-your-face. I especially love how the first track starts off nearly silent with the plucked instrument (I think it's the kantele you mention in your description), before that dramatic swell midway through. Makes me imagine I'm exploring a narrow almost claustrophobic cave that opens up to an enormous underground temple. Very cinematic in its sound and build-up.
The instruments used are very fitting for the theme and I love that you used your own vocals in such a unique way. Overall just lots of interesting details that layer onto each other with excellent mixing. I've always found it challenging adding so many different sounds without becoming too "structured" but you pull it off very well. Amazing work!