Original: I think that starting out with big open perfect 4ths in the synth give your track a celestial quality right out of the gate, while the seashore sound effects immediately set the scene of gently floating on the water. I think you have great harmonic variation between the A and B sections which make this song loopable without feeling too repetitive.
Pirates: With the last song being in D major, my ears were tricked into thinking that the first chord was also a D major even though there isn’t a D present. I am impressed how you were able to subvert my expectations many times in this piece just like the sneaky pirates. I really like the use of chromatic chord transitions. The use of accordion also works very well for a pirate theme!
Night: This is such a peaceful theme. The use of only high-register instruments makes me think of twinkling stars. I really like the introduction of the ii chord in the B section. It adds an extra layer of questioning before moving back to V for a nice perfect cadence.
Underwater: I agree with you that I think this is also my favorite of your 4 themes! The use of the chromatic mediant in the B section adds some really interesting uplifting colors to this piece. I love the IV-I-V ending! The synth swells and underwater sound effects are also nice touches that really make this feel like an underwater theme. This is a very nice submission - thank you for sharing!