The title theme has such a nice vibe to it; gentle yet progressive. Great choice of instruments here - they all complement one another and weave between each other. Nice job on the orchestration, too - does exactly what it needs to to bolster the rest of the instruments in the mix.
Under Water Conversations nails the underwater vibe; dreamy spaciousness with just the right amount of top end. Pleasant melody here, kept nice and simple to really drive home that floating feeling. I like the choice of patch for the pad below leading the progression.
Finally, Under Water World Theme is gorgeous off the bat. A nice rounded arpeggio to kick things off and then that familiar soft-synth atop guiding the lead tones. Having the arpeggio open up a little more as the track progresses is a nice touch and the bounciness of it does a great job of emulating that floating deeper and deeper feeling. The more elaborate voicings toward the end are great too, prevents melody fatigue.
Great work all in all, solid selection of 3 tracks that all execute on the theme really well. Production is perfect too, no issues on my end. Best of luck! :)